Turkey’s military carried out airstrikes targeting Kurdish militants in northern Iraq on Sunday, just hours after the Kurdistan Workers’ Party (PKK) claimed responsibility for a deadly bombing in the capital in the latest attack of its nearly four-decade long insurgency.

In a statement, the Turkish Defense Ministry said its warplanes destroyed 20 PKK targets including caves, bunkers, shelters and warehouses in the regions of Metina, Hakurk, Kandil, and Gara.

“Many terrorists were neutralized by using the maximum amount of domestic and national ammunition,” said the statement, which cited self-defense rights from Article 51 of the United Nations Charter to justify the strikes.

The PKK, which is classified as a terrorist organization by Turkey, the United States, and the European Union, earlier said it was behind the blast Sunday outside Turkey’s Interior Ministry building that left one dead and two injured, the pro-PKK Firat News Agency reported.