As Russia pressures Ukraine, the US military is increasing its presence in a tense corner of Europe nearby

• The US military has been increasing its presence on the ground and at sea around southeastern Europe.
• The region’s location near the Black Sea and Eastern Mediterranean Sea give it strategic importance to NATO and Russia.

The US military is expanding its presence in southeastern Europe and around the Black Sea region amid heightened tensions with Russia over its military buildup around Ukraine.

With a conflict in Ukraine appearing more likely, Washington wants to reassure its NATO allies by increasing its ability to deter and respond to Russia’s actions in the short-term and by laying the groundwork for an increased footprint in the region for the future.

A strategic region

Southeastern Europe is strategically significant for NATO and Russia alike.

The region borders the Black Sea, which offers access to Russia’s southern front, often described as its underbelly, and the Eastern Mediterranean Sea, which connects Europe, the Middle East, and North Africa and overlooks vital maritime routes between the continents.

During the Cold War, all southeastern European countries, except neutral Yugoslavia and Western-allied Greece, were part of the Soviet-led Warsaw Pact.

The region’s geopolitical balance has since changed: Slovenia, Slovakia, Croatia, Bulgaria, and Romania have joined NATO and the EU. Albania, North Macedonia, and Montenegro recently joined NATO and have applied to join the EU.

However, Russian influence remains considerable. The Kremlin maintains strong relationships in the Western Balkans by leveraging cultural, ethnic, and religious ties.

Moscow recently underscored the importance it places on the region by calling on NATO to withdraw its forces from Bulgaria and Romania, which have taken a greater role in the alliance’s security architecture — Romania by hosting more forces and Bulgaria by supporting NATO movements by land, sea, and air.

Strengthening NATO’s flank

Romania hosts the only active Aegis Ashore site in Europe. The system “is designed to protect European NATO Allies and US deployed forces in the region against the growing threat posed by the proliferation of ballistic missiles,” according to US European Command.

Aegis Ashore is a defensive system, but Moscow suspects it could be repurposed for offense and has criticized the site in Romania and one under construction in Poland.

Romania’s Aegis Ashore site began operating in 2016, and the US military has expanded its presence there in the years since. Last week, the US reinforced its rotational presence in Romania by relocating 1,000 troops there from Germany and by sending a number of F-16s. Other NATO militaries also have troops temporarily stationed in the country.

Yet Romanian President Klaus Iohannis has called for “a more consistent” US and NATO presence in the Black Sea region. His calls might now be answered.

At a summit on February 16 and 17, NATO’s defense ministers agreed to look into establishing battlegroups in “Romania and other countries in the east, central and southeast of the Alliance,” according to NATO Secretary-General Jens Stoltenberg.

NATO currently has four battlegroups, totaling 4,500 troops, stationed in Poland, Latvia, Lithuania, and Estonia. Those units were set up in response to Russia’s 2014 annexation of Crimea.

Bulgaria may also host one of the future battlegroups. The US military is present in four bases in Bulgaria, most notably Bezmer Air Base. However, the Bulgarian government is wary of antagonizing Russia, with which it has a good relationship.

In December, Bulgaria’s defense minister, Stefan Yanev, dismissed the notion of additional NATO troops being deployed to Bulgaria.

Following the NATO summit, however, Yanev said Bulgaria would accept a few hundred foreign troops but specified that any battlegroup would be under Bulgarian command and would only conduct training and exercises.

More US troops are already on their way to Bulgaria. A US Army Stryker company stationed in Vilseck, Germany, will travel there in the coming days to train with Bulgaria’s military. (A 2006 agreement limits the number of US personnel in Bulgaria to 2,500.)

On the other side of the Balkans, Albania recently agreed to host a forward-operating base for a small number of US special-operation troops. The base will shorten the time it takes American operators to deploy to the region and allow those operators to build ties with their Albanian counterparts, potentially increasing American influence there.

The most visible signs of the US’s increasing presence in the region are farther south.

Creating links

The US military frequently trains with its Greek counterpart, but the US has underscored the value of Greece as an ally by signing recent agreements that will give it more access to and presence at Greek facilities.

In October, Washington and Athens renewed and updated their Mutual Defense and Cooperation Agreement, which Secretary of State Antony Blinken called “the bedrock” of the countries’ defense cooperation. (US-Greek ties have improved amid worsening relations between the US and Turkey, Greece’s neighbor and longtime rival.)

Under the agreement, the port of Alexandroupolis in northeastern Greece will become a transportation hub that allows the US to deploy troops and equipment to the Black Sea region more quickly.

In October and November, the US performed its two largest disembarkation operations ever in Greece through Alexandroupolis, showcasing the port’s significance.

The US already uses a naval base at Souda Bay on the island of Crete, in the heart of the Eastern Mediterranean, and thanks to the updated MDCA it will be able to expand its presence at other bases across mainland Greece.

Greece wants to maintain its working relationship with Russia despite the current tensions, but that may be a difficult balance for Athens to strike as Moscow has already expressed dismay about the increasing US presence there.

For the US, the closer partnerships with Greece and its neighbors have been welcome.

Following the summit last week, Defense Secretary Lloyd Austin said he had never seen the alliance “more relevant and more united” and expressed confidence that it would be “sure-footed in the face of aggression.”

Constantine Atlamazoglou works on transatlantic and European security. He holds a master’s degree in security studies and European affairs from the Fletcher School of Law and Diplomacy.