The Pacific Concerns Resource Centre says the US military should remove its nuclear weapons it says are held at bases in Guam.
The pressure group based in Fiji says it's greatly alarmed by reports about the crash of the nuclear-powered submarine, the USS San Francisco, in Micronesia last week.
It says a nuclear accident would be catastrophic for the region, not only threatening human lives, but destroying marine resources and everything dependent on it.
The PCRC says for the US navy to deny the likely effects of such an accident is an insult to the intelligence of Pacific people.
It says the deaths and terminal cancers suffered by Marshall Islanders and the Chamorro people of Guam should be testimony enough to the dangers of nuclear weapons, which it says remain one of the US military's best kept secrets.
The US military is carrying out an investigation in Guam into how the submarine ran aground, killing one crewmember.
It has assured the Micronesian government that no radioactive material leaked out in the incident, and added it was standard policy not to say whether the submarine had nuclear weapons on board.