A senior US general has expressed concern over the "expanding reach" of the Pakistan-based Lashkar-e-Taiba (LeT) militant group.
Admiral Robert Willard, head of the Pacific Command, told a Senate hearing that the group was no longer solely focused on India or South Asia.
LeT is one of the largest and best-funded militant groups in the region.
It is blamed for the November 2008 attacks on Mumbai (Bombay), in which gunmen killed more than 165 people.
Adm Willard said the group had declared a jihad (holy war) on America and had carried out attacks on US forces in Afghanistan, although India continued to be its main target.
He said that the US had evidence of LeT's presence in Europe, the broader Asia-Pacific region and even in Canada and the US itself.
"Unquestionably they have spread their influence internationally and are no longer solely focused in South Asia and on India," Adm Willard told the Senate Armed Services Committee.
He said that the relationship of the Pakistani government to LeT "is a very sensitive one".
The US was working with Nepal, Bangladesh, Sri Lanka, the Maldives and India to help build their capacities to contain the militant group, he said.
Adm Willard's comments on Tuesday came on the same day that reports emerged saying Pakistan had asked the US to reduce the number of CIA agents in the country and to limit drone strikes along the Afghan border.
Correspondents say that LeT was cultivated by Pakistan's security apparatus 20 years ago to fight a guerrilla war to wear down Indian security forces in Kashmir.
The group is outlawed in Pakistan, but India maintains that Pakistan's security forces retain ties to the militants.
Adm Willard also said that India and Pakistan were unlikely to resolve their dispute over Kashmir in the immediate future because of the fragile government in Islamabad.
"Unquestionably there remains a level of tension across the border that is very hard to impact," he said.
"And given the turmoil that has been in Pakistan for the past couple of years, it's hard to imagine that the fragile governance in Islamabad is going to rise to a level where the impasse can be broken in the near term."