It has been one year since Donald Trump took office for a second term as United States president, and he marked the occasion with a marathon news conference in the White House briefing room, where he zig-zagged between topics ranging from immigration to the future of the United Nations.“ It’s been an amazing period of time,” Trump said as he took the podium on Tuesday, armed with a stack of printouts.Recommended Stories list of 3 itemsend of listFor more than one hour and 40 minutes, the Republican leader ran through a list of his accomplishments, touting a trend of “reverse migration” away from the US and what he called “high economic growth”.But the briefing was overshadowed by fraying relations between the US and its traditional allies in Europe, as Trump presses ahead with his campaign to own the self-governing Danish territory of Greenland.European leaders had started to gather at the World Economic Forum in Davos, Switzerland, on Tuesday, where Trump’s threats to acquire Greenland “one way or another” cast a pall over the proceedings.Some leaders, including Canadian Prime Minister Mark Carney, even suggested it was time for Western allies to imagine a future without US leadership. “We are in the midst of a rupture, not a transition,” Carney told his audience at Davos.In his news briefing, Trump himself suggested that international institutions like the United Nations and t …