Ukrainian President Volodymyr Zelenskyy warned Thursday that recent drone incursions showed Russia was seeking to escalate its aggression, while offering Europe his country’s battlefield expertise to counter the threat.

European leaders from just under 50 countries converged on a conference center in Copenhagen under tight security after mystery drone flights rattled Denmark.

The drone sightings in Denmark and high-profile aerial incursions by Moscow in Estonia and Poland have heightened fears that Russia's assault on Ukraine could spill over Europe's borders.

"The recent drone incidents across Europe are a clear sign that Russia still feels bold enough to escalate this war," Zelenskyy said.

"It was never just about Ukraine, Russia has always aimed to break the West and Europe," he added.