The president also ruled out sending U.S. ground troops to Ukraine but said air support could be given as part of security guarantees. Meanwhile, hundreds more National Guard troops are expected to arrive in Washington in the coming days as Republican-led states offer to send additional soldiers to back up Trump's federal takeover of the nation's capital.

President Donald Trump offered his assurances that U.S. troops would not be sent to Ukraine to defend against Russia, after seeming to leave open the possibility.