U.S. ships are returning to the Red Sea following promises from Yemen’s Houthi rebels to abstain from attacks on American and British vessels. The pledge, which comes after more than a year of

Shipping companies expressed caution about using the shorter route between Asia and Europe that many ships have avoided for more than a year.

Yemen’s Iran-backed Houthi movement has released the crew of a cargo ship more than a year after its fighters hijacked the vessel in the Red Sea, as part of its campaign of attacks in support of Hamas in its war against Israel.

Six ships linked to the U.S. and U.K. have successfully transited the area without coming under attack since January 19.

Despite recently touting a Suez route, Mediterranean Shipping Company (MSC) said it will stick to Cape of Good Hope until further notice.

The second reason is politics. The Houthis have made it clear that any re-opening of the route is contingent on the modalities and progress of the ceasefire between Israel and Hamas, the implementation of which began on Sunday. “There are still many ifs and buts to the situation,” the executive said.

The world’s top three container operators said they fear instability in Gaza and broader regional tensions mean continued danger.

Yemen’s Houthi rebels have signaled they will limit their attacks in the Red Sea corridor to only Israeli-affiliated ships as a ceasefire in the Gaza Strip takes hold.