Israel has rushed warships to the Red Sea, where US naval assets are also patrolling, after Yemen's Houthis declared "war" earlier this week. The Houthis had also reportedly launched a ballistic missile at Israel, and released a video showing the launch. In total the Houthis are believed to have attempted three drone and missile attacks on Israel. One of the initial projectiles days ago had been intercepted by a US warship off Yemen, and another was stopped as follows: 

The Israeli military on Tuesday used its Arrow missile defence system for the first time to intercept an "aerial threat" over the Red Sea, believed to have been a ballistic missile.

According to newly released Israeli military images, Sa’ar-class corvettes are now patrolling near Eilat port in the Red Sea.

They will be monitoring skies over the Red Sea and around Israel after the Yemeni rebel group widely seen as backed by Iran has vowed to "help the Palestinians to victory."

While apart from Gaza, Israel has been most focused on the Hezbollah threat on the northern border - having engaged in daily exchanges of fire with the militant group in southern Lebanon - the Yemeni action raises the specter of the situation spiraling into a broader regional war.

Sporadic fire along the occupied Golan Heights, and Israel's attacks south of Damascus, also raises the possibility of the Gaza war spilling into Syria. 

According to fresh reporting in The New York Times, the Houthis are already escalating their attacks on faraway Israel:

Yemen’s Houthi militia claimed an attempted attack on southern Israel on Tuesday, saying it had launched a “large batch” of ballistic and cruise missiles as well as drones toward Israeli targets.

The Iran-backed militia carried out the attempted assault in response to what it called “brutal Israeli-American aggression” in Gaza, the Houthi military spokesman, Yahya Sarea, said on the social media platform X. Mr. Sarea said the attack was the third operation conducted by the Houthis “in support of our persecuted brothers in Palestine,” and threatened further missile and drone assaults.

The Houthis have been locked in a war with Saudi Arabia (and allies UAE & the US) since 2015. In 2014 the Shia rebel group overran the Yemeni capital of Sanaa, sparking the Saudi-UAE intervention to uphold the pro-Saudi government. Many tens of thousands have been killed over the last half-decade of fighting, with the country also on the brink of starvation. 

Disagreement persists among analysts over whether the Houthis possess missiles that could effectively reach Israel.

The US and Israel have long accused Tehran of shipping weapons to the Houthis. It's believed that their surprisingly sophisticated missile arsenal comes from the Iranians, and these have been used to attack Saudi Arabia several times, including strikes on Saudi Aramco oil facilities.