NATO scrambled two German Eurofighters in response to a Russian military aircraft over the Baltic Sea on Sunday. The aircraft, which could not initially be identified, was flying in international airspace without a flight plan or radio contact,

This was the latest event after a series of incursions by Russian military aircraft into NATO airspace in September, leading to heightened tensions between NATO and Russia.

The UN Security Council will hold an emergency meeting on Monday to discuss Russian incursions over Estonia’s airspace, Estonian and UN officials said Sunday.

Here is how the NATO alliance's advanced aircraft carriers compare. America's newest Gerald R. Ford-class aircraft carriers are led by the USS Gerald R. Ford. The new fleet nuclear-powered "flattops"—10 are planned—is set to gradually replace the Nimitz class.