The Bush administration has formally notified Congress of its intention to proceed with a fighter-jet sale to Pakistan worth up to $5 billion. Pakistan is to purchase as many as 36 new-model F-16 fighter aircraft and may also acquire some used F-16's.
The Congress will have 30 days in which to reject the offer to Pakistan.
However that is considered unlikely, since the Bush administration has been consulting informally with key members of the Senate and House for several months and no major objections have been raised.
The State Department said the deal calls for Pakistan to purchase 18 new F-16's with an option to buy 18 more.
The United States will also upgrade Pakistan's existing fleet of 34 old-model F-16's, and the South Asian country would also have the future option of buying 26 used aircraft from U.S. inventories.
A munitions package and logistical support for the planes are also part of the deal.
The Bush administration first announced its intention to make the offer to Pakistan in March of last year, as it was also beginning talks on a new strategic relationship with India including help for that country's civilian nuclear program.
A State Department spokeswoman said the F-16 sale is aimed at cementing the U.S. strategic partnership with Pakistan, and will not upset the military balance with India.
She said India has its own plans to upgrade its air force, and that the two South Asian powers have a dialogue underway and have reduced tensions over the long-running Kashmir dispute.
The F-16, which has long been on one of the mainstays of the U.S. Air Force, has been upgraded many times since its introduction in 1979.
Pakistan acquired its F-16 fleet in the mid-1980's and had contracted to buy more, but the deal was blocked by a 1989 Congressional ban on arms transfers because of Pakistan's then-covert nuclear weapons program.
The suspended sale of the aircraft, some of which Pakistan had paid for, was an irritant in bilateral relations for many years.
But the relationship warmed markedly after the September 2001 terrorist attacks amid cooperation by Pakistan in the war against international terrorism including support for the U.S.-led invasion of Afghanistan.
The administration's notice to Congress of the F-16 sale to Pakistan came just after Secretary of State Condoleezza Rice visited the South Asian country on Tuesday, though officials here said the timing was coincidental.
The officials said the go-ahead for the sale could have come earlier, but that the Islamabad government delayed the purchase because of the need to focus resources on recovery from the devastating earthquake in northern Pakistan last October.