NATO allies convened in Ankara on Tuesday ahead of the alliance’s annual leaders’ meeting to address ongoing efforts to increase defense spending in response to U.S. pressure and regional security concerns. The summit comes nearly one year after former President Donald Trump urged NATO members to raise their defense budgets substantially, targeting 5 percent of gross domestic product (G.D.P.) by 2035.

Mark Rutte, NATO’s secretary general, highlighted progress in a defense industry forum held in Turkey, emphasizing that several allies had already boosted their military expenditures significantly. According to NATO data released on Tuesday, overall spending on member countries’ armed forces increased by $90 billion in the last year. Five nations are on track to meet or exceed the 5 percent G.D.P. threshold this year.

However, the picture remains uneven. While countries such as Germany, the Baltic states of Estonia, Latvia, and Lithuania, Poland, and Greece are making considerable investments in modern weaponry and troop levels, others face financial or political challenges. Spain, for example, has maintained defense spending at about 2 percent of G.D.P., despite Trump’s demands, with Prime Minister Pedro Sanchez stating that higher targets are unnecessary for Spain’s military priorities. Similarly, Britain, grappling with recruitment and retention issues, is projected to spend around 2.7 percent on direct defense needs through 2029 and faces uncertainty on reaching the higher benchmarks.

Some smaller nations have struggled to meet even the lower NATO targets. Albania and Slovenia failed to reach the 2 percent threshold last year. In Albania, public opposition to increased military spending complicates government efforts, despite recent legislative moves to raise defense investment to 2.2 percent of G.D.P. Slovenia has focused on infrastructure projects, such as upgrading transport routes from the Port of Koper to Hungary, which officials describe as critical for military logistics. Yet NATO leadership, including Rutte, criticized Slovenia for including spending on projects that do not fully align with agreed definitions of core defense expenditure.

The NATO spending guidelines adopted last year call for 3.5 percent of G.D.P. to be devoted to direct military priorities, such as troops and equipment, with an additional 1.5 percent permitted for defense-related infrastructure. Some member states have pushed these boundaries, allocating funds to broad infrastructure improvements that may have limited military value. The Czech Republic’s recent inclusion of a rail upgrade to a tourist site in its defense spending report drew particular scrutiny from analysts, who question the military relevance of such projects.

U.S. officials have warned that allies failing to increase spending risk reductions in American military assistance, including financing for purchases of U.S. weapons systems. Speaking at the summit, U.S. Ambassador to NATO Matthew Whitaker underscored the expectation that all allies will urgently align with the 5 percent spending commitment.

The impetus to increase defense budgets is tied both to long-standing transatlantic debates over burden-sharing and more immediate security threats. Russia’s invasion of Ukraine has brought renewed focus on Europe's ability to deter aggression without heavy reliance on U.S. military support. While financial concerns remain significant, analysts note that NATO’s broader aim is to ensure the alliance maintains sufficient forces and capabilities to respond effectively to emerging challenges.

As NATO members continue negotiations, the balance between political will, domestic constraints, and strategic necessity will shape the alliance’s capacity to meet the demands of collective defense in a rapidly evolving security environment.