Ukraine is sharing its expertise in drone defense with European countries KYIV, Ukraine -- The Ukrainian military is sharing with European countries its expertise in fighting Russian drones, sending a mission to Denmark for joint exercises,

Danish Prime Minister Mette Frederiksen called it “the most serious attack on Danish critical infrastructure to date.”

Denmark's defense ministry reported more drone sightings overnight Saturday into Sunday at several of its armed forces' locations.

The vessel had its tracking equipment deactivated, indicating the vessel wished to avoid detection by Danish authorities.

More drones spotted in Denmark over military sites as Nato vows to ramp up vigilance - Dozens have been injured in a sustained attack on Kyiv and other parts of Ukraine by Russia

Denmark's defense chief has called a series of unidentified drones being spotted near airports and military installations a "hybrid attack."

Denmark will impose a blanket ban on civilian drone flights ahead of a visit by European leaders to Copenhagen next week.

Denmark says it will ban all civilian drones this week over safety concerns as Copenhagen prepares to host an EU summit on European defense.

Denmark reported to NATO allies that unspecified "state actors" were responsible for drone incursions that shut two airports, Latvia's foreign minister told Reuters on Thursday, but Danish officials said it was still unclear who was behind the incidents.

Boosting NATO's presence close to Denmark sends "a message of assurance and cohesion within the Alliance," says a spokesperson.