A Greek oil tanker is stuck in the Red Sea after it was attacked by Houthi rebels, an Iran-backed militia group that controls swathes of northern Yemen and has disrupted crucial shipping lanes in a show of solidarity with Palestinians in Gaza.

The MV Delta Sounion has been immobilized for more than a week, making it a sitting duck for further attacks while also raising fears of an environmental disaster. The tanker was carrying the equivalent of one million barrels of crude oil.

The Sounion, its crew evacuated, currently sits in waters patrolled by Houthi vessels. The Houthis have said they will allow a rescue mission, but moving the ship will be precarious.

Here’s what we know about the stuck tanker.

How did the ship get stuck?

The MV Delta Sounion was sailing through the southern Red Sea when it came under attack from vessels controlled by Houthi fighters on Aug. 21, according to the European Union’s naval mission in the Red Sea, the Indian Ocean and the Gulf.

No crew members were killed or injured, but the ship lost engine power during the attack, the naval mission said on social media. The crew of 23 Filipino and two Russian sailors was evacuated to Djibouti, a country on the Horn of Africa.