NATO has taken over air defenses in Poland from the US just days before the inauguration of President-elect Donald Trump, according to a NATO spokesman, with questions looming about the incoming administration’s approach to the alliance and to Ukraine.

NATO's current target for members' defense spending is 2 percent of their country's GDP. Trump has repeatedly called on the alliance to increase this amount.

Even before being sworn in, Donald Trump harshly criticized European NATO countries. He also changed his stance on ending the conflict in Ukraine, suggesting he could achieve it within half a year, not in 24 hours as he previously claimed.