As the United States has reduced its troop presence in the past few years, the war’s toll — civilian casualties aside — has fallen on the Afghan forces and the Taliban. That is reflected in the casualty numbers: While a total of more than 100,000 Afghan forces and Taliban are believed to have been killed, the number of coalition deaths stands at a little more than 3,500.

“We are making staggering sacrifices in human life to defend not only our country, but also to hold at bay those forces which threaten global security,” Mr. Mohib, the Afghan national security adviser, said.

In a sign of the government’s fragility, heavy fighting broke out on Thursday in Mazar-i-Sharif, the largest city in northern Afghanistan, between Afghan special forces sent from Kabul and militiamen and police officers loyal to a former governor, Atta Mohammed Noor. Mr. Noor had threatened violent resistance after President Ashraf Ghani’s government named a new provincial police chief, which Mr. Noor said violated a promise that he would have influence over key appointments.

“Afghan security forces are tasked with protecting the Afghan people, not fighting each other over political disputes,” John Bass, a seemingly frustrated U.S. ambassador to Kabul, tweeted in a call for de-esecalation.

The possibility that the United States might agree to withdraw troops from Afghanistan just as the war has intensified, and before a comprehensive political settlement is finalized, has raised fears that the war could devolve into revenge-taking and a fight over power once the Americans are gone.

Mullah Baradar called on his fighters to show humility, though he also reinforced the idea that the Taliban already see themselves as triumphant. Now that God has “given them victory in political and military fields,” he said, they “shouldn’t resort to ego and pride.”

“They should show humility, and show gratefulness to God,” he said. “Instead of a desire for power, they should think about service to Islam and the people.”

He added, “My advice to them, my request to them, is that they not be arrogant and grandiose, and they should act in a way with the people as a father would do with their children — with kindness.”