British and American ships are tentatively returning to the Red Sea after Yemen’s Houthi rebels vowed to hold off attacks on vessels linked to both nations, a sign that traffic on one of the world’s main trade routes could normalize after more than a year of disruption.

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

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

Suez Canal Authority Chairman Osama Rabie has told shipping giant AP Moller-Maersk there are signs of stability returning to the Red Sea, and urged the company to take that into account when planning sea routes,

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

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.

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.

Mandeb strait decreased by 50% after the Yemeni rebels launched maritime attacks, according to the US Energy Information Administration.