DUBAI, United Arab Emirates — Yemen’s Houthi rebels signaled Monday they now will limit their attacks in the Red Sea corridor to only Israeli-affiliated ships after a ceasefire between Israel and the Hamas terror group began in the Gaza Strip, but warned wider assaults could resume if needed.

The terrorists’ announcement, first made in an email sent to shippers and others late Sunday, likely won’t be enough to encourage global firms to reenter the route that’s crucial for cargo and energy shipments moving between Asia and Europe. Their attacks have halved traffic through the region, cutting deeply into revenues for Egypt, which runs the Suez Canal linking the Red Sea to the Mediterranean.

“The ceasefire is considered fragile,” said Jakob P. Larsen, the head of maritime security for BIMCO, the largest international association representing shipowners.

“It is assessed that even minor deviations from the ceasefire agreements could lead to hostilities, which would subsequently prompt the Houthis to again direct threats against a broader range of international shipping.”

That was underscored by a speech aired Monday from the Houthis’ enigmatic supreme leader, Abdul-Malik al-Houthi.

We are “maintaining constant readiness to intervene immediately should the Israeli enemy resume any escalation, commit acts of genocide, impose a siege on Gaza or deny food and medicine to the people of Gaza,” al-Houthi said. “We are ready to return to escalation again alongside our brothers, the fighters in Palestine.”

The Houthis made the announcement through their Humanitarian Operations Coordination Center, saying it was “stopping sanctions” on the other vessels it has previously targeted since November 2023.

For Israeli ships, those “sanctions… will be stopped upon the full implementation of all phases” of the ceasefire, it added.

However, the center left open resuming attacks against both the United States and the United Kingdom, which have launched airstrikes targeting the rebels over their seaborne assaults.

“In the event of any aggression… the sanctions will be reinstated against the aggressor state,” the center said. “You will be promptly informed of such measures should they be implemented.”

However, the shipping industry reacted with caution to the Houthi pledge.

“The coming weeks will provide the proof of whether the Houthi follow suit with their stated intent,” the maritime security firm Ambrey warned.

The Houthis have targeted over 100 merchant vessels with missiles and drones since the Israel-Hamas war in the Gaza Strip started in October 2023 with Hamas’s onslaught in Israel in which terrorists murdered some 1,200 people and took 251 hostages.

The Hamas-run Gaza health ministry says more than 46,000 people in the Strip have been killed or are presumed dead in the fighting so far, though the toll cannot be verified and does not differentiate between civilians and fighters. Israel says it has killed some 18,000 combatants in battle as of November and another 1,000 terrorists inside Israel on October 7.

Israel has said it seeks to minimize civilian fatalities and stresses that Hamas uses Gaza’s civilians as human shields, fighting from civilian areas including homes, hospitals, schools and mosques.

The Iranian-backed Houthis have seized one vessel and sunk two in a campaign that has also killed four sailors. Other missiles and drones have either been intercepted by separate US- and European-led coalitions in the Red Sea or failed to reach their targets, which have also included Western military vessels.

The rebels had maintained that they target ships linked to Israel, the US or the UK to force an end to Israel’s campaign against Hamas in Gaza. However, many of the ships attacked had little or no connection to the conflict, including some bound for Iran.

The tempo of Houthi attacks has slowed in recent weeks, particularly involving ships at sea. That may be due in part to the US airstrike campaign. The US and its partners alone have struck the Houthis over 260 times, according to the International Institute for Strategic Studies. Israel has also launched several rounds of airstrikes on Houthi targets.

However, the rebels have continued to launch drones and missiles targeting Israel, which has warned it will continue to strike Houthi leadership.

Another wild card is US President Donald Trump, who started his second term Monday. He may reapply a foreign terrorist organization designation on the Houthis that former president Joe Biden revoked, which could spark attacks again.

“Uncertainty is further exacerbated by today’s inauguration of Trump,” Larsen said. “It remains unclear how the Trump administration will act in the conflict with the Houthis and whether potential punitive actions against them will be considered.”

Times of Israel staff contributed to this report.