Germany has sent planes to track a Russian military aircraft after it was intercepted flying without a plan or radio contact in a neutral airspace over the Baltic Sea.
The German Air Force said its "quick reaction alert force", ordered by NATO on Sunday, came amid rising tensions in the region following Moscow's incursion into Estonia's airspace in recent days.
Russian jets were observed flying in Estonian airspace for more than 10 minutes on Friday, an incursion condemned by President Donald Trump.
President Donald Trump on Sunday said he would defend the EU members and Baltic states if Russia intensified hostilities.
When asked by reporters, Mr Trump said: "Yeah, I would. I would."
The incident has prompted an emergency meeting of the UN Security Council on Monday.
The two German E