A possible attack by Yemen's Houthi rebels on Monday targeted a ship further away from nearly all of the previous assaults they've launched in the Gulf of Aden, officials said, potentially part of a widening escalation by the group.

The attack comes as the U.S. has sent the USS Dwight D. Eisenhower back home after an eight-month deployment in which it led the American response to the Houthi assaults. Those attacks have reduced shipping drastically through the route crucial to Asian, Middle East and European markets in a campaign the Houthis say will continue as long as the Israel-Hamas war in the Gaza Strip rages on.

The attack happened Monday morning in the Gulf of Aden about 280 miles southeast of Nishtun, a town in the far reaches of Yemen that's close to the border with Oman, according to the British military's United Kingdom Maritime Trade Operations center. That region for long has been held by forces allied to Yemen's exiled government, which has battled the Houthis since the rebels took the capital, Sanaa, back in 2014.

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The attack was just off to the northeast of Yemen's Socotra Island, also held by allies of the exiled government.

"The master of a merchant vessel reports an explosion in close proximity to the vessel," the UKMTO said. "The crew are reported safe and the vessel is proceeding to its next port of call."

It offered no other immediate information about the attack.

Suspicion immediately fell on the Houthis, who did not immediately claim the assault. It can take the rebels hours or even days to acknowledge their attacks. Somali pirates have been known to operate in the region as well, though they typically seize vessels for ransom rather than launch attacks against them.

However, the attack happened near the outer reaches of the Gulf of Aden where it becomes the Arabian Sea and then ultimately the Indian Ocean. Of the more than 60 attacks launched by the Houthis since November that specifically targeted vessels, this would be one of the furthest.

In May, a Portuguese-flagged container ship came under attack by a drone in the far reaches of the Arabian Sea in an attack claimed by the Houthis. However, the distance at which it was struck led experts to question whether Iran, the Houthis' main benefactor, could have launched the attack. The Houthis have claimed attacks later assessed to have been conducted by Iran, including the 2019 attack on Saudi Arabia’s oil fields that temporarily halved the kingdom’s energy production.

The Houthis have made a series of claims without evidence they've targeted vessels at even greater distances, even though there's been no independent confirmation of any of those attacks actually taking place.

The rebels have fired off other missiles and drones in their campaign that has killed a total of four sailors. They have seized one vessel and sunk two since November. A U.S.-led airstrike campaign has targeted the Houthis since January, with a series of strikes on May 30 killing at least 16 people and wounding 42 others, the rebels say.

The Houthis have maintained that their attacks target ships linked to Israel, the United States or Britain. However, many of the ships attacked have little or no connection to the Israel-Hamas war — including those bound for Iran.