ISLAMABAD, Pakistan -- Prime Minister Benazir Bhutto used a visit Tuesday by U.S. Defense Secretary William Perry to demand that Washington either deliver F-16 fighter planes or return the $650 million Pakistan paid for them.


"We want either the planes or our money back," Bhutto told reporters at her official residence hours after Perry arrived in Islamabad for talks. "We think this is all very unfair."


Pakistan and the United States are longtime allies, but relations have been troubled over the stalled fighter deal and Pakistan's controversial nuclear program. Pakistan agreed to buy 71 planes in 1989 and paid $650 million, enough for about half of them.


Washington stopped military and economic aid to Pakistan in 1990, believing it had acquired a nuclear weapon, and has refused to refund the money.


Under a sanction known as the Pressler Amendment, the United States also has refused to return Pakistani military equipment, such as helicopter parts, sent to America for repairs.


Bhutto stressed that she wants to rebuild relations with Washington and said Perry's visit showed a "broadening of the relationship above and beyond the impediments of the Pressler Amendment."


Perry was expected to meet with Bhutto and Army Chief of Staff General Abdul Waheed.


Defense Minister Shahban Mirani, who met Perry at Chaklala Air Force Base, said Pakistan will not sign agreements on the nuclear issue unless its traditional enemy, India, does the same.


Perry said the United States considers Pakistan "an old and valued friend," but also acknowledged the disagreements. "There are differences between the U.S. and Pakistan -- no two nations can agree all the time," Perry's statement said.


Mirani also ruled out international inspections of Pakistan's nuclear sites, something Washington has been pushing for, unless India submits to similar inspections. "We'll be telling him to sort it out with India," Mirani said.


Pakistan and India have fought three wars since the subcontinent gained independence from Britain in 1947.


India conducted a nuclear test in 1974 and is believed to be capable of making a nuclear bomb.


Perry will visit India on Thursday.