Mullah Mansour was a threat to US

"They were specific things that we knew he had engaged in or was preparing to engage in, that were directly threatening coalition and US forces," Pentagon spokesman Jeff Davis said on Monday.

"This [Mansour] was an individual who was specifically targeting US and coalition personnel and had specifically engaged in operations in the past that had resulted in US and coalition personnel being killed," he added.

US President Barack Obama approved the strike based on a law authorizing US military force in Afghanistan, the Pentagon said.

The operation against Mansour was strictly in keeping with the rules and in continuance with the US conducting strikes of a defensive nature, according to the Pentagon spokesman. Pakistan has protested the drone attack, saying it was a violation of its sovereignty.

The US and the NATO officially ended combat operations in Afghanistan 2014, but their forces still carried out defensive strikes against militants.

Mullah Mansour was killed a US drone strike last week at Pakistan's border with Afghanistan. Mansour became the head of the Taliban after the death of its previous leader, Mullah Omar. Afghan officials had initially considered Mansour a proponent of peace talks with the government, but the militant group has refused to participate in further negotiations.

mg/bw (AP, Reuters)