Pentagon officials confirmed to Fox News Thursday that Navy SEALs had been, and were still, involved in the inspection of a possibly radioactive container ship off the coast of New Jersey.

The Liberian-flagged M/V Palermo Senator was ordered back to sea by the Coast Guard Wednesday after traces of radioactivity were found in the hold during a routine inspection at the Port of Newark.

The 708-foot freighter, owned by a German subsidiary of South Korea-based Hanjin shipping, was anchored in an exclusion zone six miles from shore.

The Pentagon sent a team, including demolition experts, to try to determine if there are radioactive materials on a ship detained off the coast of New Jersey, officials said Thursday.

The specialists were sent after one test earlier in the week showed traces of radioactivity in the cargo of the M/V Palermo Senator-- and a second test turned out inconclusive, defense officials said.

The Liberian-flagged container ship was ordered to remain in a security zone six miles offshore while the inspection continues, the Coast Guard said.

Authorities were alerted to a possible concern about the ship's cargo as it made its way to the United States with stops in Asia and the Middle East, top trouble regions in the Bush administration's war on terrorism, two officials said.

The ship is believed to have made stops in Indonesia, Malaysia and Egypt, one defense official said on condition of anonymity.

Defense Department spokesmen declined to say what the Pentagon team went to do on the ship Thursday, offering only that a team with special capabilities was sent to assist the FBI, which is in charge of the investigation.

But another official, asking not to be identified further, said that the team included experts in detecting and disposing of explosive ordnance.

The ship was directed to a berth at the Port Newark/Elizabeth Marine Terminal after a Coast Guard team boarded the vessel Tuesday. Team members reported hearing suspicious sounds in several of the ship's cargo holds, but found no evidence of stowaways and said they could not determine the source

But trace radiation could come from a number of sources, such as clay, pipes that have been used for a long time underground in oil excavation, defense officials said.

The Associated Press contributed to this report.