Washington is “increasing the legitimacy of the Taliban,” Mr. Mohib said. “And decreasing the legitimacy of the Afghan government.”

Such concerns were underscored by a recent television interview with the Taliban spokesman Zabihullah Mujahid, who said, with what many considered a triumphalist tone, that the insurgents would see themselves as returning “victorious.”

Mullah Baradar tried to ease some of those fears in his message.

“Those who come to an understanding with us, and they don’t cheat us or seek enmity, we will treat them like our brothers,” he said. “I am hopeful that all issues will be resolved, the countrymen should not be concerned.”

He added: “Nobody has any thoughts of prejudice. It is our Islamic country, and all Afghans should sit together, show respect for each other, and we should have mercy on each other.”

Some Taliban fighters and field commanders have a very different concern, fueled by news reports and rumors that their political leaders — many of whom have spent the war away from the battlefield — could compromise on some of their fundamental demands.

Many Taliban field commanders, speaking on the condition of anonymity to avoid angering their political leaders, said that while they trusted them, they would accept nothing less than a full withdrawal of foreign forces — and soon. Their concerns seem fueled by reports that the United States wants to leave a residual force in Afghanistan for counterterrorism purposes.

“In all these meetings, in all these days, I can’t think of a point or a thought that may have gone against our principles,” Mullah Baradar said, seemingly responding to those fears.