As NATO leaders convene in Ankara for their annual summit, the alliance is witnessing a marked shift in its power dynamics, with European members assuming greater responsibility for collective defense and military operations. Over the past year, European countries have significantly increased defense spending, expanded arms production, and taken on senior command roles within NATO—developments driven in part by pressure from the United States under President Donald Trump.

European defense expenditures have risen at their fastest pace in decades. According to NATO Secretary-General Mark Rutte, European allies and Canada have collectively increased their defense budgets by approximately $1.2 trillion over the last decade, with spending rising nearly 20% in the past year alone. This surge reflects an effort to address long-standing American criticism that Europe has relied too heavily on the U.S. for its security.

European governments are moving beyond financial contributions to actively leading NATO efforts in critical regions such as the eastern flank, the Baltic states, and the Arctic. They are also playing a larger role in arming Ukraine amid its ongoing conflict. Rutte characterizes this shift as a strategic rebalancing rather than an American retreat, though underlying concerns remain about the United States’ reduced presence in Europe.

The alliance is navigating complex timing challenges: the United States is cautious about relinquishing military capabilities too quickly, while European states are striving to build their capacities to fill emerging gaps. Notably, Europeans have assumed command of all three regional NATO Joint Force Commands previously led by American officers, and U.S. contributions to NATO’s combat power could drop to about half as early as next year.

This transition raises questions about Europe’s ability to develop the political and military leadership necessary to match its growing defense obligations. The United Kingdom, while reaffirming its commitment through recent defense announcements by Sir Keir Starmer, still faces challenges meeting NATO’s 3.5% defense spending target and addressing aging military equipment.

European governments also confront the complex balance between increasing military budgets and funding domestic welfare systems, historically supported by American security guarantees that allowed lower defense spending. Meanwhile, NATO’s capabilities lag behind those of potential adversaries. Russia allocates roughly 40% of its budget to defense and maintains continuous military production, while China, North Korea, and Iran continue to expand their capabilities.

Heightened tensions stemming from the Iran conflict have further strained transatlantic relations. European governments expressed frustration over a lack of consultation before U.S. engagement, while Washington criticized Europe's reluctance to join U.S. military operations. The dispute has intensified debates within NATO about burden-sharing and strategic priorities.

A pressing concern is the depletion of missile and ammunition stocks, as Europe, the United States, and Ukraine simultaneously rely on limited supplies. Ukraine’s ongoing need for weapons will serve as an immediate test of the durability of recent transatlantic cooperation.

As NATO’s summit unfolds, officials aim to present an optimistic front, crediting recent efforts for strengthening the alliance. Whether this momentum satisfies the United States, however, remains uncertain. NATO is increasingly evolving into an alliance where Europe is expected not only to contribute more funding but also to take on greater command responsibilities, supply more resources, and ultimately lead more of the alliance’s collective defense.