A US drone strike targeted the leader of the Taliban, Mullah Akhtar Muhammad Mansour, US officials said Saturday, in a rare US incursion inside Pakistan since Navy SEALs killed Osama bin Laden, Al Qaeda’s leader, in 2011.

Pentagon press secretary Peter Cook said the military was still assessing whether Mansour was killed in the strike, which was carried out by an unmanned drone.

Cook said Mansour was “actively involved’’ in planning attacks in Kabul and across Afghanistan, and had been “an obstacle to peace and reconciliation between the government of Afghanistan and the Taliban, prohibiting Taliban leaders from participating in peace talks with the Afghan government that could lead to an end to the conflict.’’

A US official, speaking on the condition of anonymity, said the strike occurred around 6 a.m. Eastern time Saturday, and that both Mansour and a second fighter traveling with him in a vehicle were probably killed. Even so, officials offered caution because early assessments of the deaths of militant and terrorist leaders in US strikes have proved inaccurate in the past.

The drone strike, authorized by President Obama, took place in a remote area of Pakistan along the border with Afghanistan, southwest of the town of Ahmad Wal. The strike was carried out by several unmanned aircraft operated by US Special Operations forces, the official said.

News of the strike came as General Joseph Votel, head of the US Central Command, was completing a secret trip to northern Syria, where he visited US Special Operations forces and met with local fighters being trained by the United States in the battle against the Islamic State. Votel is the highest-ranking US military official to travel to Syria during the war.

But the strike against Mansour served as a reminder that even as the Obama administration has talked of an end of combat operations in Afghanistan and is focusing on the fight against the Islamic State in Iraq and Syria, the fighting in Afghanistan and the risk of rising militancy therehave continued.

“Since the death of Mullah Omar and Mansour’s assumption of leadership, the Taliban have conducted many attacks that have resulted in the death of tens of thousands of Afghan civilians and Afghan security forces as well as numerous US and coalition personnel,’’ Cook said.

Mansour had long remained a mystery to US policy makers and the US military. In the 1990s, he was the Taliban government’s chief of aviation while Afghanistan had few planes; he also oversaw the tourism department when there were few tourists.

But in the years after the Taliban leadership was driven into exile in Pakistan in 2001, Mansour became central to the group’s reincarnation as a powerful insurgency. After the death of the Taliban’s founder, Mullah Muhammad Omar, Mansour became the group’s supreme leader and the architect of the most recent insurgent assault that swept across northern Afghanistan.

But even as he was acting leader of the Taliban, he kept secret the fact that Omar had been dead since 2013.

Unlike Omar, Mansour did not live in hiding. Some of the time he lived in a southern neighborhood of Quetta, Pakistan, in an enclave where he and other Taliban leaders from the same Pashtun tribe, the Ishaqzai, had built homes. And although he is on the United Nations no-fly list, he has repeatedly taken flights in and out of Pakistan, Afghanistan officials said, to Dubai, where he has a house and investments under different names.

Even as the Taliban operating inside Afghanistan remain a formidable and violent force, Mansour has had difficulties uniting his ranks after months of infighting. In April, for example, a Taliban spokesman said the new leader had appointed the brother and son of Omar to senior leadership posts.

Mansour has faced criticism and even outright rebellion from field commanders who distrusted his ties to Pakistan and his handling of the succession. He brutally quashed breakaway groups and sought to buy the support of other skeptical commanders, all while maintaining a publicity campaign that has portrayed him atop a united command.