Belarusian dictator Alexander Lukashenko called Lithuania’s decision to close the two countries’ borders a “crazy gamble.” 

Lithuania shut its border with neighboring Belarus after a wave of balloons entered its airspace last week, prompting airport closures and significant travel disruptions. On Sunday night alone, Lithuanian authorities detected 66 objects heading from Belarus into Lithuania.  

Lukashenko slammed the move as “absurd” and “a crazy gamble,” according to Belarus’ state-run news service. 

“Even for a small country, Lithuania, it is petty,” he said, adding: “We are not talking about any extraordinary smuggling.” The Belarusian strongman, who has cracked down on civil dissent in his country, is one of Russian President Vladimir Putin’s closest allies.

Lithuanian Prime Minister Inga Ruginienė said Monday the balloons, used to smuggle cigarettes, were a “hybrid attack” and vowed to respond with the “strictest measures,” including shooting them down. 

She also did not rule out invoking NATO’s Article 4, which convenes the alliance’s member countries for urgent talks. 

Lithuania’s roughly 680-kilometer border with Belarus was temporarily closed pending a government meeting on Wednesday, which will likely result in it being shut indefinitely. However, diplomats and EU nationals leaving Belarus will still be able to cross.

European countries, from Denmark to Estonia, have struggled with how to defend their skies in recent weeks following a spate of incursions by drones and jets linked to Russia. Danish Prime Minister Mette Frederiksen declared last month that the continent is embroiled in a “hybrid war.”