Nearly 30 years ago, Peter Willcox was captain of the Greenpeace ship the Rainbow Warrior when it was blown up by French agents. Today, the American is in a Russian jail, accused of piracy after members of his latest Greenpeace crew tried to board an offshore oil platform in the Arctic in a protest against drilling.

Willcox, now the 60-year-old captain of the Arctic Sunrise, was among 22 Greenpeace activists from around the world who were ordered detained for two months this week by a court in Murmansk, a Russian port above the Arctic Circle. After a hearing that began early Thursday morning and concluded at 2 a.m. Friday, the court delayed a decision on eight other detainees. They include the group’s spokesman, Dima Litvinov, who has dual Swedish American citizenship.

Russia detained two activists on the rig Sept. 19 and seized the ship in the Pechora Sea on Sept. 20, towing it to Murmansk, where it arrived Tuesday. Conviction on piracy charges could bring up to 15 years in jail.

“Our ship was seized in international waters, and that was a mistake,” Daniel Simons, a Greenpeace lawyer, said Friday, addressing a Moscow news conference via Skype from Murmansk.

The only legal grounds for seizing a ship in those waters, Simons said, are illegal fishing, illegal broadcasting, causing serious pollution or piracy. The Arctic Sunrise was guilty of none of those crimes, he said, and piracy requires two ships.

“There is a clear difference in international law between a ship and a fixed platform,” he said.

Even President Vladimir Putin, who was attending an Arctic Forum in a town near the Arctic Circle earlier this week, said the Greenpeace environmentalists were not pirates. However, in attempting to board the platform, he said, “they violated international laws.”

Last year, Greenpeace carried off a similar protest on the same rig, said Kumi Naidoo, executive director of Greenpeace International, who took part. No one accused those activists of piracy.

Willcox would have followed the same kind of maneuver, Naidoo told reporters in Washington on Friday. He would have kept the Arctic Sunrise about 500 yards away from the Prirazlomnaya rig — which is owned by a subsidiary of Gazprom, the giant energy corporation controlled by the Russian government — and is not yet operational. Activists in small inflatable boats would have approached and tossed a rope over a protrusion on the rig. Last year, they unfurled a banner, set up a small tent and stayed there 12 hours.

This year, the two who climbed aboard were quickly detained, Naidoo said, and 11 warning shots were fired into the water around the inflatable boats.

When Willcox refused to sail away the next day, Russian coast guard members dropped onto the ship from helicopters, he said.

It was the stiffest response that Greenpeace has encountered since the bombing of the Rainbow Warrior in 1985, said Phil Radford, executive director of Greenpeace USA. The Rainbow Warrior was on a mission to protest French nuclear testing when it was blown up while docked in New Zealand. One crew member died.

Greenpeace officials said Willcox cares deeply about the environment and has spent years fighting to protect it.

“He’s cool, calm and collected,” said Naidoo, who sailed with him last year. “The people of the United States should be proud one of their fellow citizens is involved in this fight.”

Greenpeace wants the world to designate the upper Arctic a “global common place,” protecting the fragile environment from drilling and threats of spills.

Earlier this week, a spokesman for Russia’s main investigative body said the Greenpeace activity was clearly suspicious. “When a foreign vessel full of electronic technical equipment of unknown purpose and a group of people calling themselves members of an environmental rights organization try nothing less than to take a drilling platform by storm, logical doubts arise about their intentions,” Vladimir Markin said.

A Russian freelance photographer, Denis Sinyakov, and a British videographer, Kieron Bryan, were also ordered held for two months, even though they were journalists documenting the voyage. In protest, a half-dozen or more Russian news Web sites replaced their usual photographs with blacked-out spaces Friday.

Dmitri Artamanov, a Greenpeace representative in Murmansk, said the organization had been given no information about the Arctic Sunrise until Thursday.

“There were illegal searches of the ship,” he said Friday. “Our activists were locked up, and all their belongings, computers, phones, everything, were taken away.”

U.S. Embassy officials in Moscow said they had met with Willcox and Litvinov. “We are following their cases with great concern,” the embassy said in a statement. “We are also in close touch with Russian authorities to ensure the well-being of these individuals, and their continued access to legal counsel while in detention.”

Englund reported from Washington.