After incidents occurred in Poland, Romania and Estonia, NATO has warned Russia that it would take all necessary measures to defend its airspace against any further violations. NATO on Tuesday accused Moscow of an escalating campaign of airspace violations over eastern and northern alliance member states. Danish Prime Minister Mette Frederiksen called the incident "the most serious attack on Danish critical infrastructure." Ukraine's Volodymyr Zelenskyy condemned the incident on X as a violation of Danish airspace by the Kremlin. NATO chief Rutte said it was "too early to say" whether the drone flights over Denmark were connected to Russia's recent violations of NATO airspace.