Since the early Cold War, the United States has been the center of the transatlantic security architecture. Every NATO Supreme Allied Commander Europe (SACEUR) has been American, and as of late December 2024, 38,500 U.S. Army soldiers were deployed across the region. However, since taking office in January, the Trump administration has begun to reprioritize how and where the U.S. Army is deployed. Their recently released U.S. National Security Strategy has shifted significant focus to the Western hemisphere and countering the PRC in the Indo-Pacific.
In order to prepare for future contingencies in these regions, the Army is adjusting its force posture in Europe. At the end of October, the Department of War announced that a rotational brigade previously stationed in Romania would not be replaced once it returned to its home unit in Kentucky. The number of U.S. troops in-country would be reduced to around 1,000. Key American capabilities in areas such as air defense and intelligence that European Allies lack will not be removed. Additionally, strategic assets used by the U.S. and other NATO Allies, like the Mihail Kogălniceanu (MK) Air Base and Deveselu ballistic missile defense site, will be unaffected. Further force reductions have been planned to take place in Bulgaria, Hungary, and Slovakia as soon as mid-December 2025.
Pentagon officials have stressed that this shift should not be viewed as America withdrawing from involvement in the European theater. No force adjustments have been planned for the Baltic states or Poland, areas of the Eastern Flank assumed most likely to face direct military threats from Russia once the war in Ukraine ends. This decision has instead been framed as a recognition of increased European preparedness to take on conventional defense of the continent. However, heads of the House and Senate Armed Services Committees, Senator Roger Wicker and Representative Mike Rogers, have warned that the move risks undermining NATO’s collective deterrence posture. Removing troops from Romania, the member state closest geographically to active frontline zones in Crimea and other parts of occupied Ukraine, may embolden Russia. Moscow may take this as a sign to escalate its airspace violations and sabotage attacks ongoing across the Eastern Flank.
Keeping this in mind, any further U.S. Army troop reductions in the region must be offset by sustained technological and logistical support, most critically in the air domain. Capabilities that remain in Europe must be agile, able to augment Allied forces and be scaled in the event of a crisis. One possible approach for the U.S. would be substituting the removed rotational brigades with predominately-unmanned drone units, ideally housed in the Army Reserve. Small, inexpensive counter-unmanned aircraft systems (C-UAS), like those used in Ukraine, should be prioritized for operational use by Reserve Forces. Training to do so should be undertaken for intelligence collection and strike missions, with systems configured for multiple-payload use. By adopting this approach, Reserve troops would be able to serve as a force multiplier for those of other Eastern Flank Allies. This would allow U.S. Army Europe and Africa Command (USAREUR-AF) to strategically augment partner forces where they are most lacking.
Despite regional shifts in the U.S.’s international military posture, Europe remains the “frontline of North America’s shores.” In a world where Russia, the PRC, and other revisionist powers see their futures as interlinked, it is vital the U.S. and Europe view theirs in the same way. Any weakening of U.S. support for NATO may convince Russia and the PRC that Ukraine and Taiwan would go similarly undefended. Augmented by creative adaption of emerging technologies, continued U.S. leadership will be vital in ensuring deterrence holds across regions.
Gabriella Calder is an American analyst focused on conflict, politics, and security in the former Soviet Union. She writes on the Black Sea, Caucasus, and NATO-Russia dynamics across the broader region.
