Still, it is a far cry from the nearly 300 American military trainers and other personnel operating in Pakistan just a few years ago. The last of about 125 Special Forces trainers, who advised scores of Pakistani Frontier Corps paramilitary soldiers in different locations, left Pakistan a year ago when tensions between the two countries spiked following the Navy SEAL raid that killed Osama bin Laden.

Reuters reported Wednesday that fewer than 10 American Special Operations soldiers had been sent to a site near Peshawar to train paramilitary troops. But two American officials said Thursday that the deployment, at least for now, was less ambitious and involved two regular military officers, not Special Operations soldiers, serving as liaisons and not trainers.

The mini-deployment comes as American and Pakistani negotiators are finishing a fifth week of fruitless talks in Islamabad in an attempt to work out details of reopening NATO supply lines that flow through Pakistan into Afghanistan. “I wouldn’t categorize this as a positive sign for progress on broader issues; that’s way too much wishful thinking,” said one senior American military official who spoke on the condition of anonymity because he was not authorized to discuss the issue.

Against this backdrop, underscoring the rancorous, uneasy alliance that is central to the Obama administration’s plan to end the war in Afghanistan, the American diplomatic leadership in both Pakistan and Afghanistan is changing this summer.

Two American officials said this week that the administration was expected to name Richard G. Olson as the new ambassador to Pakistan, replacing Cameron P. Munter, who is leaving this summer after two years on the job. Mr. Olson is an assistant ambassador at the American Embassy in Kabul, responsible for economic affairs and development.