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.

Six ships linked to the U.S. and U.K. have successfully transited the area without coming under attack since January 19, when the Houthis said they would stop targeting vessels associated with those countries, according to the Joint Maritime Information Center, which collates information on the militants’ attacks from multiple navies.

“JMIC assesses that as the peace agreement progresses and vessels and infrastructure remain untargeted, improved stability is expected; however, the risk in the Red Sea and Gulf of Aden remain elevated,” it said in a recent report.

The Houthis announced the partial halt to attacks in response to a ceasefire agreement between Israel and Hamas in Gaza, following a more than yearlong campaign that disrupted global trade. The group said U.K. and U.S.-linked ships would be allowed to pass starting on January 19. Vessels wholly owned by Israeli citizens or companies, or sailing under the Israeli flag, remain at risk. 

If the safe passage holds, it could give other shipping companies that continue to avoid the Red Sea confidence to return. Industry giants like Denmark’s A.P. Moller-Maersk A/S, Switzerland’s MSC Mediterranean Shipping Co. SA and Japan’s Mitsui OSK Lines Ltd. have all said they wouldn’t immediately resume transits despite the assurances, citing lingering uncertainty around security.

The attacks have forced many vessels to take the longer route around Africa to avoid the Red Sea, extending journey times and adding to shipping costs.