Yemen’s Houthi rebels are stepping up their missile attacks, keeping up what could be the last major front in the Middle East wars.

Israel launched a multi-wave attack across Yemen in retaliation for Houthi missile and drone strikes, the Israeli military confirmed Thursday.

The head of the World Health Organization said he was about to board a flight in the Yemeni capital when the airport came under bombardment.

The Israel Defense Forces continues its intense airstrike and ground campaigns in Gaza, particularly in the north of the strip around several Palestinian hospitals.

Israel is signaling a wider campaign against Houthi militants in Yemen, a mountainous and impoverished country more than 1,000 miles from Israeli territory.

Israel’s military says it intercepted a missile fired toward the country by Yemen’s Houthi rebels. The attack set off sirens late Monday in central areas of Israel, including Tel Aviv.

Air raid sirens rung out in Jerusalem after a missile was launched from Yemen towards Israel, according to the Israeli military. (AP video by Yesica Fisch and Sam Mednick)

The US military on Tuesday said it hit targets in Yemen targeting the Houthi militia, hours after the Iran-backed group launched attacks on Israel. The United States Central Command (CENTCOM) said its warships and aircraft attacked a number of Houthi-linked sites,