The US carried out another round of strikes against the Houthis in Yemen, according to three US officials, marking the fourth time the US has struck the Iran-backed rebel group in less than a week.

The US used Tomahawk missiles to target approximately 14 Houthi missile launchers used to attack international shipping lanes, one of the officials said. The Tomahawk missiles were launched from US Navy surface vessels and the USS Florida, a guided missile submarine, another official said.

The US strikes are the latest in a series of actions against the Houthis, following significant US-led strikes last week with the UK, and support from a handful of other allies. They come amid heightened tensions in the Middle East and fears that the Israel-Hamas war in Gaza could further spill out into the region.

Hours earlier, the Houthis struck a US-owned and operated vessel for the second time this week. The Iran-backed rebel group used a one-way attack drone to target the M/V Genco Picardy in the Gulf of Aden, according to US Central Command. No one was injured on board the commercial vessel, Central Command said in a statement. The ship suffered some damage but was able to continue on its way.

On Monday, the Houthis struck another US-owned and operated vessel with an anti-ship ballistic missile in what appeared to be the first such successful attack against a US asset since the group being attacking international shipping lanes in mid-November.

The US has been seeking to avoid major escalation in the region as fears rise over the conflict between Israel and Hamas in Gaza spilling out into the region. And despite the Houthis saying the attacks are in protest of Israel’s military campaign in Gaza — as well as US and coalition forces coming under regular attacks in Iraq and Syria, and Israel and Hezbollah fighting over the Israel-Lebanon border — the Pentagon insisted Wednesday that the Israel-Hamas conflict has not spread.

“Clearly there are tensions in the Middle East. There have been tensions there since the Israel-Hamas conflict has kicked off … But to answer your question, no, we currently assess that the fight between Israel and Hamas continues to remain contained in Gaza,” Pentagon spokesman Maj. Gen. Pat Ryder said at a press briefing.

The new strikes also come the same day the US re-designated the Houthis as a Specially Designated Global Terrorist (SDGT) entity.

“These attacks are clear example of terrorism and a violation of international law and a major threat to lives, global commerce, and they jeopardize the delivery of humanitarian assistance,” a US senior administration official told reporters on Tuesday.

While the US said last week that the strikes would degrade the capability of the Houthis to continue carrying out attacks on commercial shipping in the Red Sea, the Houthis have continued to do so. A US official told CNN previously that in total, last week’s strikes destroyed roughly a third of the Houthis’ overall offensive capabilities.

Officials have since said that they expect some level of retaliation by the Houthis. Indeed, on Monday in what appeared to be the first time a US-owned and operated ship was hit by the Houthis, a cargo ship – the M/V Gibraltar Eagle – was struck by an anti-ship ballistic missile.

And on Tuesday, the Houthis launched an anti-ship ballistic missile into the international shipping lanes of the Southern Red Sea — just hours after the US targeted four anti-ship missiles in more strikes.