US lawmakers have rejected a blunt challenge to President Barack Obama's war strategy, defeating a resolution calling for American troops' removal from Pakistan by a crushing 38-372 margin.

The resolution proposed by Democratic Representative Dennis Kucinich and Republican Representative Ron Paul would have required the Obama administration to pull American military trainers out of Pakistan by the end of the year.

Citing the 1973 War Powers Resolution, introduced after the Vietnam War, Kucinich had said that the Obama administration had violated the Act, as it "only allows the President to send US armed forces into military operations abroad if the Congress approves the decision or if the US is under a serious threat or attack".

"We have known that US forces have been operating in secret inside the territories of Pakistan without congressional approval," The Daily Times had quoted Kucinich, as saying while proposing the bill.

"It is our constitutional responsibility as members of the Congress to act," he added.

There are about 200 military personnel in Pakistan, and up to 120 are assigned to train the Pakistani military in the tribal areas along the border with Afghanistan.

The US Special Operations Forces has also been allowed to operate alongside Pakistan military's Frontier Corps on humanitarian missions.

However, US officials had said that the teams join the Pakistani troops only when commanders determine that there is relatively little security risk.

The U.S. troops are allowed to defend themselves and return fire if attacked, but the official emphasized the joint missions are not supposed to be combat operations.

Pakistan, however, has publicly stuck to its long stated objection of allowing any foreign troops from operating on its soil. (ANI)