NATO’s deputy commander has said he wants a summit in Turkey to spur member countries to spend more on defense, reaffirm support for Ukraine and underline the unity of the alliance.

Air Chief Marshal John Stringer, NATO Deputy Supreme Allied Commander in Europe, spoke to The Associated Press in London less than two weeks before the crucial Ankara summit on July 7-8 tests the cohesion of the 77-year-old alliance.

US President Donald Trump has sent conflicting signals over America’s force posture in Europe and has threatened to leave the alliance. He has also unnerved European leaders with his push to annex Greenland and his flattery of NATO adversary Russian President Vladimir Putin. US Defense Secretary Pete Hegseth lambasted NATO allies last week for not allowing use of their bases to attack Iran, as he announced a surprise six-month review of American forces in Europe.

Meanwhile, in the UK – the country which holds the position of NATO deputy supreme allied commander – government ministers quit recently over what they said were military spending plans that fail to keep Britain safe.

Summits are “highly political events and they are a demonstration of any organization’s unity,” said Stringer, a senior British air force officer. It would be strange if there weren’t moments of turbulence over decades of NATO expanding, he said.