Why does Trump and NATO have a troubled relationship?

World leaders are in Turkey for the NATO summit, but a key player -- US President Donald Trump -- has had a troubled relationship with the alliance, CNN writes.
Trump has threatened to withdraw the US from NATO and has questioned whether the alliance is valid for the United States, which, according to him, covers Europe's security burden, to remain a member.
In recent months, this stance was clearly demonstrated as the US became involved in the conflict with Iran.
What does this mean: NATO's own alliance was established 77 years ago, and during that time American and European security structures have been combined. But Trump did not consult with his European and NATO allies before launching the war against Iran and attacking the alliance, as well as specific leaders, for their unwillingness to engage and help ensure the security of Hormuz Strait.
But, at the same time, Trump has taken credit for increasing defence spending by member states and has repeatedly reconfirmed his commitment to NATO's collective defence agreement.
Besides fighting Iran, another sensitive point in the relationship between NATO and Trump was the American president's threat to using the military force to take on Greenland.
Trump claimed that control over Greenland a territory in Denmark, an ally country NATO was necessary for national security and that it would take it “; whether they want it or not,”.
This was immediately condemned by the Allies and shocked the entire Western alliance. Trump later gave up this idea, but continued to threaten with customs duties those who opposed his attempt to take on Greenland by deepening division.











