Greenpeace protesters must stay away from Royal Dutch Shell's drill ships and support vessels, the anchor lines and buoys attached to them and the Barrow airport hangar and terminal that Shell is seeking to use to support its planned oil-exploration operations in the Chukchi Sea, a federal judge ruled Friday.

Greenpeace activists are even prohibited from flying drones this summer and fall over the offshore Arctic area where Shell plans to drill, according to the injunction issued by U.S. District Court Judge Sharon Gleason.

The injunction, in effect until Oct. 31, follows a well-publicized high-seas protest by Greenpeace activists who scaled one of the Shell-hired drill rigs, the Polar Pioneer, as it was being carried by a transport ship in the North Pacific Ocean. The six Greenpeace protesters camped on the Polar Pioneer for six days last month before climbing down and returning to the Esperanza, the Greenpeace ship that was shadowing the Polar Pioneer.

The injunction also expands terms Gleason established in a temporary restraining order issued April 11 against Greenpeace USA. That temporary order set up 1,000-meter buffer zones around Shell's two drill rigs and the Blue Marlin, the ship transporting the Polar Pioneer. The new injunction establishes buffer zones ranging from 100 meters to 1,500 meters for all of Shell's Chukchi fleet.

In a statement, Shell said it was pleased with the outcome.

"We don't want a repeat of previous illegal stunts; they jeopardize the safety of the people working on board and the protestors themselves," the statement said. "We're always open to an honest discussion about the challenges and benefits of exploring for energy in the Arctic, but we cannot condone Greenpeace's unlawful and unsafe tactics. Safety remains paramount."

Gleason said Shell, which initially sought the injunction after the protesters boarded the Polar Pioneer and detailed its arguments at an all-day court hearing on April 28, made a convincing legal case for special protections from Greenpeace's U.S. branch.

The company "submitted persuasive evidence that it is under a strong threat of future trespasses by Greenpeace USA in the near term," she said in her ruling. The company also demonstrated that it could suffer irreparable, though incalculable, economic harm should Greenpeace activists disrupt exploration activities. In addition, any on-site protests by Greenpeace would threaten the safety of Shell workers, contract workers and the activists themselves, Gleason said.

She was unconvinced by Greenpeace's assertion that the safe execution of the April protest showed that future protests would also be safe.

"Rather, in the Court's view, the fact that no one was injured on that one occasion was quite fortuitous and does not serve to counter the clear risk of harm that is posed when individuals are scaling uninvited onto a vessel in the middle of the ocean or onto a drilling rig in the Chukchi Sea," she said in her order.

Greenpeace argued that it has a First Amendment right to observe, document and publicize Shell's oil-exploration activities, and that it is unfair to single it out for more restrictions than those imposed by the U.S. Coast Guard. The environmental organization also challenged the court's jurisdiction over the matter, and argued that Shell's complaint should be dismissed.