Drones shut Copenhagen Airport in 'serious attack'; NATO weighs tougher Russia action

Mysterious drones that forced the closure of a major European airport were part of a "serious attack," officials said Tuesday, hours after the latest unsettling incident over the continent's skies

Mysterious drones that forced the closure of a major European airport were part of a "serious attack," officials said Tuesday, hours after the latest unsettling incident over the continent's skies.

As U.S. allies weigh a tougher response to suspected Russian incursions, NATO leaders gathered at the United Nations General Assembly in New York condemned the Kremlin for a spate of “escalatory” incidents in recent weeks and vowed to defend itself.

Authorities did not immediately assign blame for the two to three large drones that shut Copenhagen Airport — Scandinavia's largest — Monday night. But police said a hybrid attack could not be ruled out, and Prime Minister Mette Frederiksen called it “the most serious attack on Danish critical infrastructure to date.”

Norway's Oslo Airport also reopened Tuesday morning following four hours of airspace closure after a separate drone incident took place the same evening, police told Norwegian broadcaster NRK.

Trump: Putin has 'really let me down' on Ukraine peace talks01:05“I cannot rule out that it is Russia,” Frederiksen, the Danish leader, told reporters.