The top U.S. commander in Afghanistan said Monday that Taliban leader Mullah Mohammed Akhtar Mansour was an obstacle to peace and his death will have a disruptive effect on the insurgency.

Resolute Support Commander, Gen. John W. Nicholson, said during a visit to the northern province of Kunduz that Mansour rejected the chance offered by Afghan President Ashraf Ghani to participate in the peace process.

"I hope that the Taliban leadership will realize it is time to lay down their weapons and join the peace efforts, so the people of Afghanistan can enjoy peace and prosperity in the future," Nicholson said.

President Barack Obama also said Mansour's death marks an "important milestone" in the longstanding effort to bring peace to Afghanistan.

Nicholson was in Kunduz for the second time since becoming commander of the Resolute Support mission. In late September 2015, Mansour's Taliban fighters overran the city of Kunduz and held it for four days before being driven out. The takeover was a major embarrassment for President Ashraf Ghani's government.

Nicholson also met victims and families of people killed on Oct. 3, 2015 when U.S. warplanes mistakenly bombed a Kunduz hospital run by Doctors Without Borders during the offensive to retake Kunduz. The hospital was destroyed and 42 people killed in the attack, which the Pentagon said was a mistake, caused by human error.

Asadullah Amerkhail, the governor of Kunduz province, told Nicholson that, "Mansour's death will definitely have a positive impact on security. I am taking it as a positive step and I think we will now have good negotiations between the government and the Taliban."

Mansour, believed to be in his 50s, was killed when a U.S. drone fired on his vehicle in the southwestern Pakistani province of Baluchistan. He had emerged as the successor to Taliban founder Mullah Mohammad Omar, whose 2013 death was only revealed last summer.

Sediq Sediqqi, spokesman for the Afghan Interior Ministry, told reporters during a press conference in Kabul that Mansour's death could cripple the Taliban.

"This year will be the year of destruction and defeat for the Taliban, as they lost their leader. This will make them weak in all parts of the country and finally this terrorist group will be destroyed," Sediqqi said.

However the Russian presidential envoy to Afghanistan said the killing of the Taliban leader would only exacerbate the situation by hindering the negotiation process and leading to an escalation in fighting.

Zamir Kabulov told the Interfax news agency that the Taliban field commanders would not give up, and if Mansour's deputy Sirajuddin Haqqani takes over as leader of the Taliban, "He'll show everyone what's what."