WASHINGTON, JAN 2: A US daily has unravelled the mystery over the continued payment of instalments by Pakistan to the United States towards the cost of F-16 fighter aircraft even after the controversial deal fell through in October 1990.The then Bush administration invoked a 1985 non-proliferation law, known as the Pressler Amendment, in protest against Pakistan's nuclear weapons programme and banned the assistance which had been of the order of 650 million dollars a year in the 1980s.Along with it, the United States withheld the delivery of military hardware, including the F-16s, worth 1.5 billion dollars, that Pakistan had contracted and paid for. This lead to a dispute between the two countries.The Washington Post yesterday revealed that US officials had pressured Pakistan to pay for the embargoed F-16 fighter bombers even when their delivery was in doubt.It quoted sources saying that the Justice department had advised President Bill Clinton that Pakistan would probably prevail if itsued the US government in a court of law for recovery of planes or funds because documents showed that US officials had put pressure on Pakistan for ensuring continued payment.However, the daily said that many United States lawmakers believed that Pakistan had created the problem ``by deceiving Congress'' about its nuclear intentions and ``by paying for the planes'', knowing that delivery might be blocked .Pakistan continued the payment of installments between 1990-93. Only when former senior World Bank official Moeen Qureshi took over as caretaker prime minister in 1993 following the resignation of the then Prime Minister Nawaz Sharif, Islamabad stopped the payment.By then, Pakistan had paid a total of about 1.25 billion dollars for all the equipment it had contracted. Pakistan, till now, has not spelt out reasons for its continued payment after the US had invoked the Pressler law.The dispute was partially solved two years ago under the Brown Amendment. In 1996, the US delivered to Pakistanembargoed hardware worth 368 million dollars, including three P-3 Orion naval surveillance aircraft. Instead of handing over the F-16s to Pakistan, it provided for the sale of the F-116s to a third country with their proceeds going to Islamabad.The F-16 settlement was clinched in principle during Clinton-Nawaz Sharif meeting here on December 3.