Vice President Mike Pence, who was flying on Air Force II, has been summoned to return to the White House for an undisclosed situation.
Pence was flying to Manchester, NH to speak to a gathering on the opioid crisis.
All the major stock exchanges fell quickly on the news.
President Trump had nothing on his official White House schedule Tuesday.
Not sure if related but, Russian leader Vladimir Putin cancelled his meetings according to the Kremlin and is meeting with his Defense Minister.
EU Security Council has been urgently convened, according to a source with knowledge at the United Nations.
Some unnamed White House sources say there is no cause for alarm.
More to come