Pakistan’s air force launched retaliatory airstrikes early Thursday in Iran against alleged militant hideouts, killing at least nine people and further raising tensions between the neighbors.

Thursday’s attack followed one by Iran inside Pakistan on Tuesday. Both appeared to target Baluch militant groups with similar separatist goals on either side of the Iran-Pakistan border. The countries accuse each other of providing safe haven to the groups in their respective territories.

The attacks also come as the Middle East remains unsettled by Israel’s war with Hamas in the Gaza Strip. Iran also staged airstrikes late Monday in Iraq and Syria over an Islamic State-claimed suicide bombing that killed over 90 people in early January.