ISLAMABAD -- The U.S. is embarking on a $1 billion crash program to expand its diplomatic presence in Pakistan and neighboring Afghanistan, another sign that the Obama administration is making a costly, long-term commitment to war-torn South Asia, U.S. officials said Wednesday.

The White House has asked Congress for -- and seems likely to receive -- $736 million to build a new U.S. embassy in Islamabad, along with permanent housing for U.S. government civilians and new office space in the Pakistani capital.

The scale of the projects rivals the giant U.S. Embassy in Baghdad, which was completed last year after construction delays at a cost of $740 million.