Twenty Greenpeace activists have occupied a Finnish icebreaker bound for Alaska to protest Shell’s exploratory drilling plans.

According to Bloomberg News, the group boarded the Nordica on Tuesday morning. The Nordica is currently moored in Helsinki’s harbor, and it was preparing to leave for Alaska to assist with Shell’s exploratory drilling program in the Beaufort and Chukchi Seas. The activists have hung anti-drilling banners from the Nordica, and they have also locked themselves to the ship to keep it from departing Finland.

Greenpeace says that it currently does not have any intention to protest in Alaska. In an e-mail, Campaign Coordinator Dan Howells writes that Greenpeace’s “strategy has not changed in the face of the activities in Finland,” and that they are still focusing on “public mobilization as well as litigation” to keep Arctic drilling from happening this summer.

The Port of Dutch Harbor is serving as Shell’s staging ground, and the Coast Guard has planned to ramp up its security presence in Unalaska this June in the event of any protests.