As NATO prepares for its critical July 7-8 summit in Ankara, Turkey, the alliance’s second-highest military leader is framing the gathering as a make-or-break moment to lock in increased defense investment from member states, reaffirm unwavering backing for Ukraine, and demonstrate that the 77-year-old security bloc remains cohesive despite mounting internal and external pressures.
Air Chief Marshal Sir John Stringer, NATO’s Deputy Supreme Allied Commander Europe, shared his assessment in an exclusive interview with the Associated Press in London, just 10 days ahead of the summit that will put alliance unity to the test. The gathering comes at a period of unprecedented uncertainty for the transatlantic alliance, driven by conflicting signals from U.S. President Donald Trump, who has alternately threatened to withdraw from NATO, unnerved European leaders with proposals to annex Greenland, and extended public praise to Russian President Vladimir Putin, NATO’s primary strategic adversary.
Recent tensions have deepened after U.S. Defense Secretary Pete Hegseth last month criticized NATO allies for refusing access to their military bases to conduct strikes against Iran, while announcing a surprise six-month review of all American force deployments across Europe. Internal friction has also emerged within key NATO member the United Kingdom, where two senior government ministers — including former Defense Secretary John Healey — resigned in protest over what they call inadequate military spending plans that leave the nation vulnerable to rising global threats.
Stringer, a senior British Royal Air Force officer, framed current turbulence as an inevitable part of the alliance’s decades-long expansion. “Summits are inherently highly political events, and they serve as a public demonstration of any organization’s unity,” Stringer explained during the London military conference, where AP spoke with multiple senior European military leaders about both their hopes and anxieties heading into the Ankara gathering. “Over seven decades of growth and expansion, it would be odd if we never faced periods of uncertainty. Are we in one of those moments right now? The answer is yes.”
Trump has for years pressured European NATO members to take greater responsibility for their own collective defense, and with few exceptions including Spain, allies have responded with an unprecedented push to ramp up military spending amid growing Russian aggression along the alliance’s eastern flank.
Maj. Gen. Indrek Sirel, a senior commander with the Estonian Armed Forces, argued that allies must both strengthen their own domestic military capabilities and continue providing support to Ukraine to degrade Russia’s ability to project offensive power. “Europe as a whole still has significant work to do to build a credible deterrent against Russian aggression,” added Brig. Gen. Jyri Raitasalo of Finland, the NATO member that shares the alliance’s longest continuous border with Russia.
Stringer highlighted that European nations are already ramping up defense investment to build what he called a “truly credible deterrent force,” pointing to the quadrupling of 155mm artillery shell production across multiple countries as a key example. He confirmed that the summit will include discussions about expanding defense industrial production at a scale NATO has not required in decades.
A core point of uncertainty hanging over the summit is the outcome of Hegseth’s six-month force posture review, which will shape how quickly European allies must fill potential capability gaps left by shifting U.S. deployments. Earlier this year, U.S. European Command announced that Washington would withdraw some military capabilities from the continent and expect allies to cover the resulting gaps. While the Trump administration maintains that any planned troop reductions have been coordinated with allies in advance, Sirel noted that details of U.S. force positioning in the Baltic states — a core part of NATO’s eastern flank deterrence against Russia — remain unclear. He said he remains confident in continued U.S. security guarantees, but Estonia is already preparing contingency plans to adapt to sudden changes in alliance posture.
Stringer acknowledged that U.S. long-range strike and intelligence, surveillance and reconnaissance capabilities would be difficult to replace, but he expressed confidence that European allies can close any emerging gaps through a mixed “cocktail of capabilities” rather than replicating exact U.S. systems. For example, while only the U.S. operates B-1 and B-52 long-range bombers, any loss of that capability could be offset by missile deployments from ground, sea, and smaller aircraft platforms, he explained.
Allies have already expressed frustration with frequent, sudden shifts in U.S. force policy. In May, Trump confused NATO partners when he announced plans to deploy 5,000 additional U.S. troops to Poland, just weeks after ordering the withdrawal of the same number of troops from Europe. Raitasalo, who serves as Finland’s military logistics chief, noted that effective military planning depends on long-term, consistent strategy. “If you change your mind or your plans every week, every month, or even every year, you will not deliver strong, reliable results,” he said, adding that allies need firm capability pledges rather than vague spending promises.
Maj. Gen. Jonny Lindfors, Sweden’s army chief, said a successful summit outcome would produce a shared, aligned vision for adjusting NATO’s deterrence and defense postures. He called for at least an outline — if not a fully detailed strategy — for shifting defense burden sharing across the alliance to lay the groundwork for what he called “NATO 3.0.”
The United Kingdom, a longstanding leader within NATO, is already facing pressure to honor its defense spending commitments. Last year’s NATO summit saw all 32 member states agree to work toward a target of spending 3.5% of gross domestic product on core defense, with the U.K. committing to hit that marker by 2035. But Healey and another minister resigned earlier this month, arguing that the government’s proposed plan would only reach 2.68% of GDP by 2030, falling far short of what is needed to keep Britain safe amid rising threats. New British Defense Secretary Dan Jarvis has since said the nation will uphold its existing commitments, and the government has pledged to publish its full spending plan publicly.
Stringer confirmed that by the start of the Ankara summit, NATO expects all member states to outline a “credible path” to reach the 3.5% GDP target, and the U.K. is bound by that requirement just like every other ally. “The U.K. cannot assume that its historical thought leadership within NATO is enough,” Stringer said. “It has to match that leadership with matching forces and resources.”
Alliance credibility is on the line in Ankara, leaders say. Last year, NATO Secretary General Mark Rutte retained U.S. commitment to the bloc by convincing Trump that allies would deliver “BIG” progress on increasing defense spending. Stringer said this year’s summit must not only display cohesion across all 32 members, but also deliver honest conversations and concrete, credible defense plans. Raitasalo added that the meeting cannot stop at traditional communiques, roadmaps, and action plans — it must demonstrate deterrence through tangible action. If member states fail to turn promises into actual increased investment and capability, he said, NATO’s global credibility will be put at serious risk.