The U.S. ambassador has written an open letter to Pakistanis, explaining that $573 million in U.S. aid has been suspended because Pakistan has not made adequate assurances about its nuclear capability.

Washington suspended military and economic assistance Oct. 1, demanding greater assurances that Pakistan neither possesses nor wants to possess nuclear weapons.Pakistan, the third-largest recipient of U.S. aid behind Egypt and Israel, insists its nuclear program is for peaceful purposes. The 2-week-old government of Prime Minister Nawaz Sharif has pledged to go ahead with its nuclear program - even if it means losing American aid.