REVIVING NATO´S EASTERN LINE / GEOPOLITICAL FUTURES

Reviving NATO’s Eastern Line

Many countries are investing in projects that serve both civilian and military uses.

By: Antonia Colibasanu

Over the past decade, NATO’s containment line has steadily shifted eastward, stretching from the Baltic Sea in the north through the Black Sea region and into the Eastern Mediterranean. 

The move started in 2008, when Russia went to war in Georgia, but accelerated after Russia took over Crimea in 2014 and then invaded Ukraine proper in 2022. 

Yet the region remains poorly interconnected: North-south transportation corridors are sparse, with limited highways and outdated railways that fail to support the heavy and coordinated movements required for modern NATO operations. 

These gaps have been repeatedly highlighted during NATO exercises, where slow transit times, chokepoints and cross-border delays have revealed the operational cost of underinvestment.

Stress Tests

A recent summit in The Hague marked a major shift in how the alliance conceptualizes defense spending – not just because of commitments to a new 5 percent of gross domestic product target, but because, for the first time, NATO formally acknowledged non-military budgets in areas that bolster security. 

The summit also marked a notable shift in European posture as EU institutions and European NATO members signaled that they would commit more robustly than ever to the infrastructure and logistical groundwork needed for collective defense.

To be sure, Europe didn’t wake up one day only to find its infrastructure unable to cope with threats. 

Its new posture is the culmination of several years of decisions. 

The Brussels 2018 summit, for example, endorsed NATO-EU cooperation on military mobility, and EU funds were subsequently allocated to upgrade dual-use infrastructure. 

Yet these investments were never considered part of NATO’s formal 2 percent spending benchmark. 

It wasn’t until The Hague summit in 2025 that the political and strategic consensus matured enough to justify restructuring the spending pledge itself – explicitly separating defense from broader security investments while allowing both to count toward the 5 percent goal.

This restructured spending framework introduced a floor and a ceiling: Countries must allocate at least 3.5 percent of GDP to traditional defense spending, and up to 1.5 percent may be directed toward dual-use or infrastructure-related investments. 

To qualify under the 1.5 percent category, infrastructure projects must demonstrably support defense or national security objectives. 

Acceptable projects include upgrading transport routes and power grids, enhancing military mobility corridors, improving cyber and communication networks, bolstering civil preparedness systems, and expanding the defense industrial base.

This system ensures that most resources still go to core military needs while giving nations flexibility to address the logistical and resilience challenges essential to modern defense. 

While the inclusion of infrastructure was a political compromise, it made the 5 percent target more achievable. 

The new framework enables governments to mobilize funding from outside their defense ministries – from transport or interior budgets, for example – and classify relevant projects as defense-related, provided they serve troop deployment, reinforcement or strategic mobility goals.

The 5 percent of GDP defense investment pledge is ultimately a national obligation. 

Each NATO member must marshal resources equivalent to 5 percent of its own economy to strengthen collective defense. 

However, the investments that count toward this target can come from either purely national initiatives or cofinanced projects with NATO and the EU, so long as the member state contributes its own funds to eligible defense-related activities. 

Most of the dual-use infrastructure spending will continue to be financed directly through national budgets. 

If a government allocates funding for a strategic highway upgrade or a new logistics hub that meets military requirements, even if managed by civilian ministries, it can classify that expenditure under the 1.5 percent category for broader security.

Meanwhile, NATO’s common funding tools, particularly the NATO Security Investment Program, offer mechanisms to support multinational defense infrastructure projects. 

These include upgrades to critical shared assets like airbases, fuel pipelines, prepositioned storage and command facilities across NATO territory. 

When NATO funds this kind of project in a member country, that nation’s national contribution to the project (or to NATO’s broader common budget) can be counted toward its defense spending. 

The new 5 percent guideline does not designate a separate carve-out for NATO common-funded projects, but it recognizes that these pooled investments ultimately originate from national defense contributions. 

For this reason, NATO encourages allies to leverage collective initiatives, especially those focused on enhancing logistics infrastructure and rapid reinforcement capacity, to improve interoperability and burden-sharing across the alliance.

Many NATO members that are also part of the European Union benefit significantly from the EU’s Military Mobility initiatives, particularly under the Connecting Europe Facility. 

This program provides up to 50 percent cofinancing for dual-use transport infrastructure projects that meet military requirements – ranging from reinforced bridges and upgraded railway lines to improved port and airport access. 

While only the national portion of cofunded projects counts toward NATO’s 5 percent spending target, this setup allows countries to stretch their defense budgets while aligning with the strategic objectives of NATO and the EU.

The key ingredient in this process is establishing common interests with neighboring countries and working together to improve interconnectivity. 

By acting collectively, states can amplify their voice within both institutions, ensure continuity across infrastructure networks and ultimately turn individual national investments into assets that strengthen the alliance as a whole.

Though national interests in infrastructure development naturally differ across regions and countries, there is a growing body of guidance emerging from past NATO exercises that can help align those interests within the broader goals of the alliance. 

These exercises have repeatedly exposed vulnerabilities. 

Although member states are still in the process of defining their national priorities, they are also beginning to identify overlapping needs with neighbors, opportunities for cross-border cooperation and potential sources of funding. 

The eastern flank has emerged as the alliance’s new containment line, and efforts are underway to solve north-south connectivity problems.

Estonia

Recent NATO drills such as Hedgehog 2024 and Steadfast Defender tested Estonia’s transportation network. 

They showed that upgrades and host-nation support can bolster rapid troop movements but also underscored the need for additional upgrades and redundant routes (e.g., secondary roads or civilian airfields). 

For example, British Challenger 2 tanks brought in on transporters weigh about 80 tons – twice the typical road weight limit – and barely fit under some bridges. 

Estonia is spending 100 million euros, or $117 million, (half from the EU) to reinforce highway sections and widen chokepoints.

The primary route for NATO forces is the E67 “Via Baltica,” which runs from Latvia to Tallinn. 

Estonia’s rail network uses broad-gauge tracks and connects to Latvia, with major hubs near Tapa (the main NATO training base) and the port of Paldiski. 

Estonia is expanding Via Baltica into a continuous four-lane highway, reinforcing dozens of bridges and investing in dual-use infrastructure such as the Rail Baltica project and upgraded ports and airfields. 

EU Military Mobility funds are cofinancing the Salacgriva bridge on the Latvian border and other north-south rail upgrades, and streamlined border checks will speed up allied deployments. 

Latvia

Latvia anchors the center of NATO’s Baltic corridor. 

The E67 Via Baltica runs north-south through Riga, and the east-west E22/A6 road and rail line extends from the port of Riga toward Daugavpils (and then Lithuania), offering a lateral route or backup if Via Baltica fails. 

Latvia’s rail network connects with Estonia and Lithuania. 

Riga hosts a NATO brigade and can receive equipment by sea or rail.

Like Estonia’s, Latvia's infrastructure limits heavy movement. 

NATO convoys often need special approval and escorts. 

During Saber Strike and Defender-Europe, heavy trucks avoided weak bridges in rural areas. 

And because Polish rail uses a different gauge, heavy armor usually crosses the Suwalki Gap by truck, increasing wear on Latvian roads.

In 2022, Latvia received 153 million euros through the EU’s Connecting Europe Facility to build Rail Baltica, including a new rail bridge over the Daugava River. 

Road projects aim to finish high-speed segments of Via Baltica by 2030. 

Latvia’s 2023 military mobility plan funds upgrades to 34 kilometers (21 miles) of highway and the rebuilding of critical bridges. 

At the port in Riga, funds from the U.S. European Deterrence Initiative have improved piers and rail yards to handle roll-on/roll-off armor delivery. 

Exercises with civilian rail operators are also boosting Latvia’s capacity to handle NATO deployments.

Lithuania

Lithuania controls NATO’s land link to the Baltics. 

The Suwalki Gap, a 65-kilometer corridor at the Polish border, contains the Via Baltica and the planned Rail Baltica line. 

From Kalvarija, near the Polish border, Via Baltica runs north through Kaunas (where it intersects the east-west A1 motorway from Klaipeda port) and continues to Latvia. 

The Kaunas-Vilnius-Daugavpils rail line supports lateral movement toward Latvia. 

Finally, the port of Klaipeda can receive land equipment for shipment by road and rail inland.

NATO planners have long focused on the Suwalki corridor. 

Defender-Europe 2020 and Defender-Europe 2022 tested moving U.S. Army brigades from Poland to Lithuania. 

Convoys hit bottlenecks in Kaunas, where local traffic and narrow interchanges caused delays. 

After Zapad 2021, a Russian exercise simulating an attack on Suwalki, Lithuania accelerated upgrades.

The country is enlarging the two-lane stretch of Via Baltica between the Polish border and Marijampole to four lanes, supported by 60 million euros in EU funding. 

Rail Baltica conditionally opened from Poland to Kaunas in 2023, with work on the extension toward Latvia ongoing. 

A dual-use rail loading facility near Kaunas received 13 million euros of EU funding, and Lithuania is upgrading a secondary route from Vilnius to Augustow, including reinforcing eight bridges. 

NATO funded upgrades at the Pabrade training area rail spur and Klaipeda port to enable faster unloading. 

Poland

As NATO’s frontline hub, Poland hosts multiple corridors used in recent exercises: the east-west A2 motorway, which was used heavily in both Defender-Europe exercises; the north-south Via Baltica expressway; the southern A4 motorway; and a dense rail network. 

Though Poland’s infrastructure is relatively modern, many exercises exposed friction points, including bureaucratic delays, weak bridges on secondary roads and poorly maintained bridges, while under fire. 

Civilian traffic tended to congest railways.

Poland has already endeavored to resolve these issues. 

In 2024, it signed a military transport corridor agreement with the Netherlands and Germany to create a fast lane to North Sea ports. 

It has expanded the A2 motorway eastward and has upgraded its rail lines. 

It has also built or improved several infrastructure nodes, including staging bases, railheads and fuel depots. 

These and other initiatives fit squarely into dual-use categories. 

Hungary

Hungary’s location in the heart of Central Europe makes it a key transit hub for NATO. 

Three key motorways – the M1, the M43 and the M30 – link multiple NATO allies and facilitate the transportation of troops and supplies from Western Europe to the eastern frontier. 

Hungary is also constructing the M4 motorway, which will run east of Budapest to Oradea on the Romanian border. 

In terms of rail, several lines connect Budapest to Romania and Slovakia, as well as Ukraine. 

Hungary’s Papa Air Base, home to a fleet of C-17 military transport aircraft, also helps facilitate troop and equipment movement throughout the region.

Though the country’s rail network is in line with Western European standards, it has several deficiencies. 

The main rail line to Romania has limited capacity. 

During preparations for the Defender-Europe drills, there were scheduling conflicts with civilian freight carriers, suggesting upgrades and capacity expansion could be necessary. 

However, the country has launched a project to adapt key rail stations in the west to accommodate 740-meter-long trains (the NATO standard). 

Rail bridges could also become an obstacle; some are insufficient to transport extensive cargo and could create bottlenecks. 

Since 2023, the government has been working to restore dozens of bridges across the country.

More upgrades to Hungary’s road and rail networks are underway. 

The European Union is financing construction of the M4 motorway, and another highway extending to northwestern Romania is expected to be completed by 2026. 

Both projects will help ease traffic on the busy M43. In 2023, Hungary began its largest expressway upgrade program, resurfacing and reinforcing 43 percent of the country’s main roads, many of which are used for NATO transport. 

Hungary is also participating in the EU’s Network of Logistic Hubs project, which could involve hosting a regional logistics hub. 

Plans for a new military warehouse complex near Debrecen are also in the works. 

Romania

Romania has long been a primary location for NATO drills. 

At least two major motorways expedite the deployment of troops and supplies from allied forces for various exercises, including Defender-Europe and Saber Guardian. 

The Danube crossing between Romania and Bulgaria is critical not only for military mobility but also for the transport of goods from Ukraine to world markets, similar to Constanta's role in the Black Sea. 

The rail lines ending at the port of Constanta and stretching to the Curtici border crossing are also critical nodes in NATO’s transport infrastructure.

However, past NATO exercises have exposed potential risks. 

Road and rail tunnels through the Carpathian Mountains are essential to ensuring efficient transit across Central and Eastern Europe; if they are damaged, reinforcements from Western Europe would be forced into lengthy detours. 

In addition, during the 2019 Saber Guardian drills, the U.S. military had to haul tanks by rail because the country’s road network couldn’t handle them – a potentially risky solution considering Romania’s aging rail lines, unreliable trains, retired bridges and speed-restricted tracks. 

Highways through the Carpathians are limited, and roads are difficult to navigate. 

Meanwhile, the Danube is a natural barrier to efficient transport, necessitating more sturdy and reliable bridges than what’s currently available.

Recognizing these deficiencies, Romania and its neighbors have initiated major upgrades. 

Bucharest is working on improvements to the A1 and A3 motorways over the Carpathians. 

Modernization of the “corridor IV” pan-European railway is ongoing. 

In 2023, the EU agreed to fund a feasibility study for a third bridge over the Danube, aimed at facilitating north-south mobility. 

A new highway connecting Bucharest to Giurgiu/Russe in Bulgaria has also been discussed. 

In 2024, Romania said it planned to establish a “harmonized military mobility corridor” from the Aegean Sea to the Black Sea, aimed at streamlining border crossings and upgrading infrastructure. 

NATO’s Security Investment Program has also provided funding to expand fuel pipelines and storage, modernize airbases and construct a NATO logistics hub near Constanta. 

Bulgaria

NATO’s main thoroughfare in southeastern Europe runs through Bulgaria. 

Transport in this region flows through the A4 motorway, linked to the Greek border, and the E85 highway, extending to the Danube Bridge, which connects the Bulgarian and Romanian banks of the Danube River in the town of Ruse. 

The Svilengrad-Plovdiv-Ruse rail line is also a crucial connector to both Greece and Romania, as is the line running from Ruse to the port of Burgas on the Black Sea, near the site of the Novo Selo Training Area, used for joint military exercises with U.S. forces.

Infrastructure in Bulgaria, as a transit country, can have a major impact on NATO operations. 

The country has addressed past delays for military convoys at the Greek border, but the Danube is still a major obstacle, with lengthy queues forming at the Danube Bridge, one of only two crossings connecting Bulgaria and Romania across the river. 

Rail congestion and outdated tracks are also major concerns. 

Roundabouts – such as Black Sea ferries or C-17s to transport heavy equipment – have been used in the past, but Bulgaria’s terrain and infrastructure continue to present a challenge to large-scale movements.

In recent years, Bulgaria has worked with Greece and Romania to make improvements. 

Joint initiatives include rail upgrades and a long-discussed project to connect Greece’s Aegean ports by rail to Ruse and Bulgarian ports. 

The European Union is financing a second Danube Bridge near Ruse, which will link to a future high-speed rail line from Greece to Romania. 

The Bulgarian government also has plans to build four new Danube bridges and is constructing two additional highways. 

Greece

Greece serves as the southern entry point for NATO’s Eastern flank via its ports and road network. 

The standout is Alexandroupoli, which since 2019 has become a major offload hub for U.S. equipment bound for Eastern Europe. 

The roads and railways that radiate from Alexandroupoli were used in Defender-Europe 2021.

Greece’s main challenge was not so much its internal infrastructure but rather coordination and capacity at the Alexandroupoli node. 

Large volumes tend to push the port to its limits, and rail lines tend to be slow, forcing some cargo to be convoyed by road. 

Exercises suggested there were limited railcars for onward movement. 

But a bigger concern is diplomatic: U.S. movements irritated Turkey and Russia, demonstrating a strategic if not altogether physical liability.

Greece has thus embraced its role as a strategic logistics hub. 

Athens has poured a ton of investment into Alexandroupoli by dredging, building new cranes and expanding ship capacity. 

The U.S.-Greece Mutual Defense Cooperation Agreement of 2021 specifically cites Alexandroupoli for joint use, and a portion of U.S. European Reinforcement Initiative funds has gone to port improvements and a rail spur connection. 

Bolstered by EU Military Mobility funds, Greece and Bulgaria are also upgrading the Alexandroupoli-Burgas-Varna “Sea2Sea” rail corridor. 

Similar projects are underway with Romania. 

Greece’s military, meanwhile, is identifying roads and bridges for reinforcement.

Win-Win

Based on the research and patterns observed across NATO exercises on the eastern flank from 2020 to 2025, there are several potential investment priorities, repeatedly highlighted by real-world movement challenges: Bridge reinforcement and load upgrades; road and rail reinforcement in the Suwalki Gap; rail gauge and throughput bottlenecks; Danube crossing capacity and the DN5/A5 bottleneck; port capacity and rail integration; and redundant and secondary routes.

While many infrastructure upgrades are still under evaluation or in early planning stages, NATO exercises over the past five years have provided concrete, real-world evidence of their strategic value. 

These drills do more than test military readiness; they reveal the logistical bottlenecks and vulnerabilities that national planners might otherwise overlook. 

In doing so, they offer a clear platform for identifying dual-use infrastructure investments that serve both defense and civilian purposes.

The opportunity is significant. 

Projects like Rail Baltica, the A5 motorway, upgraded Danube crossings, and modernized ports not only strengthen NATO’s deterrence posture and response time, but they also enhance national resilience and reduce supply chain vulnerabilities and contribute to long-term economic growth. 

Investing in infrastructure that meets military requirements while improving trade, mobility and connectivity is a strategic win-win.