File - In this Jan. 14, 2018 file photo a plane of the United States Air Force is parked on a field at Zurich Airport in Zurich, Switzerland. US president Donald Trump will visit the World Economic Forum (WEF) in Davos. WEF says international security, the environment and the global economy will be mind at the 48th annual meeting of business leaders, civil society advocates, academics, artistic celebrities and others in the Swiss Alpine resort from Jan. 23-26. (Patrick B. Kraemer/Keystone via AP)