The post that was quoted here has been removed
Tough titty. Pakistan was perfectly aware that US law made sanctions mandatory against that nation if it acquired nuclear weapons ("Pressler Amendment"😉 and the contract was signed after it came into effect in 1985. The military dictatorship in charge of Pakistan decided to go ahead with its nuclear plans, anyway. So they got what they deserved and they were fortunate that the US ever reimbursed anything; in fact, they got over $524 million in cash and goods (not a "credit"😉.
As Christine Fair concludes:
While Pakistanis prefer to characterize the F-16 fiasco as inherently unfair, the simple fact is that Pakistan’s leadership made a strategic choice to develop nuclear weapons at the expense of taking ownership of the fleet of F-16s. Pakistan’s leadership understood the U.S. law and its likely consequences. Pakistanis need to hold their leadership to account rather than blithely blaming Washington.
http://foreignpolicy.com/2011/02/03/the-u-s-pakistan-f-16-fiasco/
Of course it is true that the Reagan administration had falsely certified to Congress that Pakistan had no nuclear weapons in order to avoid the mandatory sanctions, but lying to Congress about such matters was SOP in that administration. That Bush I finally acted as required by law should be commended.
EDIT: FP seems to restrict access to its articles; here's another link to the same Cristina Fair piece: http://marshallarmyrotc.org/documents/TheUSPakistanF16FiascoTheHalfYouDontHearAboutTheU.S.PakistanF16Fiasco.pdf