Deputy Defence Secretary Paul Wolfowitz told the House Armed Services Committee on Tuesday that failure to train Pakistan officers could mean "pushing them into the one alternative, which is the Islamic extremists".
"It's not as though if we leave them alone, nobody else will go out to recruit them," he added.
"I think one of our problems in Pakistan today is that for too long we deprived ourselves of one of the most important instruments of influence in a country where the military is one of the most important institutions."
The deputy defence secretary also called President Pervez Musharraf - who came to power in a military coup in 1999 - "a friend of the US", adding that "no leader has taken greater risks, or faces more daunting challenges from within and without".
Washington cut off military assistance to Pakistan in 1990 following the discovery of its programme to develop nuclear weapons. Sanctions were further tightened after Pakistan's nuclear tests in May 1998 and Musharraf's military coup.
However, restrictions were waived following the 11 September, 2001 attacks as the US prepared to invade Afghanistan.
In 2003, US President George Bush announced his intention to provide Pakistan with $3bn in economic and military aid over the next five years.