Pakistan’s military says the country’s army chief has met with U.S. Ambassador David Hale to express Islamabad’s serious concerns over a drone strike on Pakistani soil that killed Afghan Taliban leader Mullah Akhtar Mansur.

A May 25 military statement says General Raheel Sharif denounced “such acts of sovereignty violations” as “detrimental to relations and counterproductive for the ongoing peace process.”

The statement comes a day after Pakistani Interior Minister Chaudhry Nisar Ali Khan complained about the drone strike, saying it is “against international law” for the U.S. government to say that “whoever is a threat to them will be targeted wherever they are.”

Mansur was killed on May 21 when his vehicle was struck by a U.S. drone in Pakistan’s southwestern province of Balochistan.

On May 25, the Taliban named Mullah Haibatullah Akhundzada, one of Mansur’s two deputies, as successor.

Based on reporting by AP and Dawn