A ship near the strategic Bab el-Mandeb Strait observed an explosion in the distance Wednesday, marking what may be a new attack by Yemen’s Houthi rebels targeting the waterway that is crucial for international trade.

The explosion, reported by the British military’s United Kingdom Maritime Trade Operations (UKMTO) center, comes after a relative lull from the Houthis, following months of attacks on shipping in the region over Israel’s ongoing war on Hamas in the Gaza Strip.

The Houthis did not immediately claim responsibility for Wednesday’s blast, but suspicion fell on the group as it has repeatedly targeted ships in the same area. It typically takes the Houthis several hours before acknowledging their assaults.

The explosion happened some 130 kilometers (81 miles) southeast of Djibouti in the Gulf of Aden.

“The master of a merchant vessel reports an explosion in the water a distance from the vessel,” the UKMTO said. “Vessel and crew reported safe. Authorities are investigating.”

The private maritime security firm Ambrey separately reported the apparent attack.

The Houthis have launched more than 50 attacks on shipping, seized one vessel and sank another since November, according to the United States Maritime Administration.

Houthi attacks have dropped in recent weeks as the rebels have been targeted by a US-led airstrike campaign in Yemen, while shipping through the Red Sea and the Gulf of Aden has declined because of the threat. American officials have speculated that the rebels may be running out of weapons as a result of the US-led campaign against them and their steady usage of drones and missiles in the last months.

The Houthis have said they will continue their attacks until Israel ends its war in Gaza, sparked by Hamas’s October 7 attack, in which thousands of terrorists invaded Israel, killing some 1,200 people and taking over 250 others hostage. The Hamas-run Gaza health ministry says more than 34,000 people in the Strip have been killed in the fighting so far, a figure that cannot be independently verified and includes some 13,000 Hamas gunmen Israel says it has killed in battle. Israel also says it killed some 1,000 terrorists inside Israel on October 7.

The ships targeted by the Houthis largely have had little or no direct connection to Israel, the US or other nations involved in the war. The rebels have also fired missiles toward Israel, though they have largely fallen short or been intercepted.

The assaults on shipping have raised the profile of the Houthis, who are members of Islam’s minority Shiite Zaydi sect, which ruled Yemen for 1,000 years until 1962. The group seized Sana’a, Yemen’s capital, in late 2014. A Saudi-led coalition has been battling the group in a stalemated conflict since 2015.