Ahead of the 2026 NATO Summit in Ankara, Trump renewed criticism of the alliance, calling it a "one-sided path" and accusing European allies of failing to contribute their fair share to collective defence.
NATO Secretary-General Mark Rutte is seeking to keep Trump committed to the alliance by highlighting increased European defence spending.
Trump has shifted his focus from burden-sharing to what he calls allies' "loyalty."
US President Donald Trump has long been sceptical of NATO, much as he has been of several international organisations and multilateral agreements.
After returning to office last year, Trump withdrew the United States from USAID, the Paris Climate Agreement and the World Health Organization. He has also repeatedly threatened to pull the US out of NATO, the military alliance founded on the principle of collective defence and security.
NATO's membership is open to European countries that uphold the alliance's principles and are able to contribute to security in the North Atlantic region. The alliance currently comprises 32 member states, with the United States being one of its 12 founding members.
The 2026 NATO Summit is being held in Ankara, Turkey, from July 7 to 8. Ahead of the gathering, Trump renewed his criticism of the alliance, arguing that the relationship between the United States and its allies is not reciprocal and describing it as a "one-sided path” on Truth Social.
He had previously complained that the US "spends more money on NATO than any other country, by far, to protect them, without getting any benefit."
Seemingly referring to NATO's 2025 defence expenditure figures, Trump claimed the United States spent "$999 billion" compared with "$44.3 billion" by Poland, adding, "Others, including Germany, are much lower." NATO's 2025 estimate puts US defence spending at approximately $980 billion.
German Chancellor Friedrich Merz rejected the criticism on Friday, defending Germany's contribution to the alliance.
"Germany is doubling its defense budget within four years. This is the greatest effort we have ever made to strengthen our defense capabilities. In this respect, we have no reason to shy away from anyone," he told reporters.
"We will state this, with all due modesty, and we are doing so as the European Union’s largest member state, bearing a responsibility within Europe."
Tensions between Trump and NATO have also intensified since the Iran war, which began in late February. Several European Union member states, along with the United Kingdom, have maintained that they will not participate in the US-Israel-led conflict, arguing that it is not their war.
Trump repeatedly sought NATO's support in pressuring Iran to reopen the Strait of Hormuz, but alliance members publicly distanced themselves from the effort.
Former UK prime minister Keir Starmer told the BBC: "My decision has been very clearly that whatever the pressure - and there's been some considerable pressure - we're not getting dragged into the war."
French President Emmanuel Macron likewise said that France was not part of the war in West Asia, adding that “we are not going to get involved in this war.” He stressed that France's actions in the region were focused on protecting its citizens and allies rather than participating in the conflict, according to BFMTV.
Trump has expressed frustration over such positions. In April, he wrote on Truth Social: "NATO WASN'T THERE WHEN WE NEEDED THEM, AND THEY WON'T BE THERE IF WE NEED THEM AGAIN."
The growing rift has also been reflected in military policy. The US Defence Department plans to withdraw 5,000 troops from Germany amid a dispute between Trump and Merz over the war with Iran.
The decision came a day after Trump criticised Merz, who suggested the United States had been "humiliated" by Iranian negotiators.
The United States maintains a significant military presence in Germany, with more than 36,000 active-duty troops stationed at bases across the country as of last December.
Further deepening the rift is the issue of Greenland, an autonomous territory within the Kingdom of Denmark. Although Greenland falls under the Danish Crown, Denmark is a NATO member. Since last year, Trump has repeatedly insisted that the United States should take control of Greenland, with the White House maintaining that all options, including the use of force, remain on the table.
The US president has argued that Greenland is vital to American national security, claiming without evidence that it was "covered with Russian and Chinese ships all over the place."
Discussing security in the Arctic, Trump said: “We need that because if you take a look outside of Greenland right now, there are Russian destroyers, there are Chinese destroyers and, bigger, there are Russian submarines all over the place. We’re not gonna have Russia or China occupy Greenland, and that’s what they’re going to do if we don’t.”
However, the Associated Press reported that experts have repeatedly rejected Trump's claims that Chinese and Russian military forces are operating off Greenland's coastline. According to those experts, Russia's military activity is concentrated in the Barents Sea, off the Scandinavian coast, while both China and Russia maintain a presence in the Bering Sea, south of Alaska.
Denmark and Greenland have consistently maintained that the territory is not for sale. Denmark has also warned that any military action against Greenland would spell the end of the transatlantic defence alliance.
Six European allies have publicly backed Denmark following renewed US demands for control of Greenland.
"Greenland belongs to its people, and only Denmark and Greenland can decide on matters concerning their relations," the leaders of the United Kingdom, France, Germany, Italy, Poland, Spain and Denmark said in a joint statement.
During a White House meeting last month, Rutte sought to reinforce the alliance's value by presenting Trump with a chart titled "The Trump Trillion" in gold lettering, highlighting $1.2 trillion in additional defence spending by European allies and Canada since 2017, AP reported.
Trump, however, appeared unconvinced, saying he remained frustrated that several NATO members declined to join the US-led military campaign against Iran.
