Washington -  The Trump administration on Friday moved to eliminate the State Department unit responsible for dealing with Afghanistan and Pakistan — transferring its duties to a regional bureau whose leadership ranks have been decimated, reported US media.

The development came with less than a day’s notice. It deeply rattled US officials who say the shift leaves unclear who is responsible for handling diplomacy toward Afghanistan and Pakistan at a time when President Donald Trump is considering ramping up US military efforts in that region.

The phase-out of the office of the Special Representative for Afghanistan and Pakistan (SRAP) was put in motion under the Obama administration, and the unit had been shrinking for some time. The plan had long been to let the State Department's South and Central Asian Affairs Bureau take over the highly sensitive portfolios.

But Trump and Secretary of State Rex Tillerson have failed to fill numerous leadership positions across the State Department. And, when compared to other regional bureaus, South and Central Asian Affairs has seen unusually high levels of top staff departures. Unlike other regional bureaus, it does not even have an acting assistant secretary overseeing it.

“The Afghanistan and Pakistan function is being dissolved and transferred into a structure that has been dissolved itself,” a US diplomat familiar with the issue told POLITICO. “We’ve long planned for SRAP to go away, but the intention was for the policy to be transferred responsibly.”

Added a State Department official familiar with the situation: "There is uncertainty about the leadership of the regional bureau given recent departures."

Overall, the developments underscore the rapid erosion of leadership at the State Department under Trump and Tillerson and the potentially damaging effects it could have on US diplomatic efforts. With SRAP gone and the regional bureau's status unclear, it's not certain who will take over the many relationships built with Afghan and Pakistani diplomatic counterparts. Such relationships need constant tending, and can fade quickly.

The State Department press office did not immediately respond to a request for comment.

The diplomat said the highest-ranking official at the moment in the South and Central Asian Affairs Bureau is the acting principal deputy assistant secretary, Howard Vanvranken, whose background is more in management than policy. The man who had been serving as the bureau's acting assistant secretary, William Todd, was transferred earlier this month to help run State's human resources bureau, which has also seen leadership turnover.

Laurel Miller, the acting special representative for Afghanistan and Pakistan, bows out Friday; she was detailed to State from the RAND Corporation. Another person leaving Friday is Jonathan Carpenter, the acting principal deputy assistant at SRAP.

The US diplomat said Tillerson and his staff had been repeatedly warned about SRAP's coming phase-out and the need to transfer the policy portfolios in a proper way. But the secretary of state appears in no hurry to fill out the leadership ranks in any of his regional bureaus.

Tillerson is looking at ways to restructure the entire State Department and has indicated that one reason so many positions have been left unfilled is because he'd prefer to reorganise the building before filling all the roles. The Trump administration's budget plan envisions a roughly 30 percent cut to the State Department, so there's anticipation that Tillerson will try to cut many positions.

In any case, because many of State's leadership roles require Senate confirmation, it could be well into 2018 before the department's top levels are filled out.

Even as US diplomats appear to be increasingly sidelined under Trump, the president has given the Pentagon more deference and intends to increase its budget. That's led to growing concern that the US policy in Afghanistan will be increasingly run by military leaders instead of civilians.