Leaders will have a busy day in Ankara on Wednesday as the NATO summit will be formally launched. The alliance's European leaders aim to convince U.S. President Donald Trump to re-commit to the military alliance after Trump revived disputes over ⁠the Iran war and Greenland and launched a new wave of strikes on Iran.

On arriving in the Turkish capital on Tuesday, Trump took swipes at allies for not standing by the U.S. on the Iran war and said he might have boycotted ​the meeting had it not been for his friendship with the host, President Recep Tayyip Erdoğan.

The U.S. ​then ⁠unleashed new military strikes on Iran and revoked a license allowing Iran to sell oil in response to attacks on three tankers. It was the latest blow to a fragile cease-fire agreement in a war that is deeply unpopular in Europe.

NATO Secretary General Mark Rutte defended the new U.S. strikes as "absolutely necessary" and played down Trump's disappointment with allies as "isolated cases." "When you have a cease-fire and Iran is basically violating the cease-fire, I think it is totally crucial that the U.S. forcefully react," Rutte told reporters before the summit.

NATO on Tuesday had sought to demonstrate that its European members were heeding Trump’s calls to spend more on their own defense and rely less on the U.S. by unveiling a raft of  arms deals  worth at least $50 billion. Trump, who has harshly criticized NATO during both his first and second terms in office, said he was "very disappointed” with the alliance and that the U.S. was not "treated well" during the U.S.-Israeli war on Iran. "Why are ⁠we ⁠spending hundreds of billions of dollars, and they're not there for us? We've always been there for them,” Trump said in an appearance on Tuesday alongside Erdoğan.

Trump has accused European nations of failing to let U.S. forces use their airspace and bases on their territories during the war.

European officials have said they largely honored their commitments to U.S. forces, despite not having been consulted about a conflict that roiled their economies.

In recent weeks, Trump has singled out Italian Prime Minister Giorgia Meloni, formerly a close ally, for criticism. On Tuesday, Trump said his relationship with Meloni "became a little bad because she refused to help us" with Iran while also describing her as a "nice person." Italian officials have sought in recent days to draw a line under the spat.

Trump also said Greenland, a semi-autonomous ⁠territory of NATO member Denmark, should be controlled by the United States.

Such assertions have long strained relations between Washington and Copenhagen, both founding NATO members, and more broadly U.S. ties with Europe.

"We are ready to defend every inch of NATO, including our own territory ... Of course, we will defend the kingdom of Denmark," Danish Prime Minister Mette ​Frederiksen said in Ankara, reiterating that Greenland was not for sale. "One of the reasons why we have built NATO many, many years ago, is ​if anything happens to one of us, then everybody should stand up for each other," she said.

The 32 NATO leaders met for a dinner on Tuesday evening, but the main session of their summit takes place ⁠on Wednesday. Ambassadors from ‌all NATO members ‌have approved a summit declaration that affirms an "ironclad commitment” to collective defense. But the declaration will only ⁠be issued after it has been endorsed by the leaders.

The Trump administration has pressed ‌Europeans to boost defense spending and take on primary responsibility for the conventional defense of Europe as it seeks to shift its military focus to the Indo-Pacific.

The U.S. has also ​announced troop withdrawals from Europe, cut the forces it ⁠assigns to NATO’s defense plans, including an aircraft carrier, refueling aircraft, fighter jets and drones, and launched a ⁠six-month review of its military presence on the continent.

European leaders say they are working to take on more responsibility for the continent’s security ⁠but want a predictable and orderly transition ​to avoid any gaps in their defenses that could be exploited by Russia. European officials have said they hope Trump’s regard for Erdoğan and his good relationship with Rutte would help smooth over tensions at the summit.