President Donald Trump has arrived in Turkey for a summit of NATO, the North Atlantic Treaty Organization, as the alliance is squeezed by Russia's continuing military aggression in Ukraine and America's growing insistence that NATO members quickly beef up their defense spending.
Those pressing concerns come on top of lingering controversies surrounding the U.S.' war against Iran and its prior attempts to take over Greenland, a territory of NATO member Denmark.
Trump is a central figure in all of those issues.
"I can imagine so many issues where this could go wrong," Michael O'Hanlon of the Brookings Institution told CNBC's "The Exchange" on Monday in a preview of the summit.
A positive outcome for the gathering would include NATO making headway on sharing its military spending burden, and finding more ways to put pressure on Russian President Vladimir Putin.
Trump arrived in Ankara on Tuesday afternoon local time. He was met by Turkish President Recep Tayyip Erdogan upon arrival and headed to a bilateral meeting with him after an arrival ceremony.
Despite previous clashes with Zelenskyy, Trump is expected to meet with him in Turkey.
