Authorities have forced protesters in kayaks from a river in Portland, Oregon, where they were trying to stop a Royal Dutch Shell icebreaker from leaving dry dock and joining an Arctic oil drilling operation.
Police also tried to lower protesters who were dangling from a bridge into the water below. Sergeant Pete Simpson said safety was the main priority, and police and coast guard officers were joined by firefighters and a rope-rescue team.
A federal judge in Alaska had earlier ordered Greenpeace USA to pay a fine of $2,500 for every hour that protesters continued to block the icebreaker from leaving for the Arctic.
US district court judge Sharon Gleason ruled on Thursday in Anchorage that Greenpeace was in civil contempt because of protesters dangling off the bridge and impeding the vessel.