On December 22 a US warplane was shot down by an American ship in an incident of friendly fire. The F/A-18 Super Hornet was flying from the USS Harry Truman when it was engaged by the guided-missile cruiser USS Gettysburg.

The incident illustrates the increasing complexity facing the US and Israel as they seek to retaliate against the Iranian-backed Houthis. The goal of their operations is to deter the Houthis from further attacks. The Houthis have attacked shipping in the Red Sea and they continue to target Israel with missiles and drones. With Hezbollah weakened and Iran cut off from its proxy by the fall of the Assad regime, the Houthis now pose as the proverbial “last man standing” in the Iranian axis in the Middle East. Deterring them may be difficult.

On December 21 a missile launched by the Houthis from Yemen hit a playground in Jaffa in southern Tel Aviv. It wounded several people. Video appeared to show the missile flying past several interceptors. This raises questions about whether Israel’s air defence systems operated as they should. Israel has successfully intercepted numerous Houthi ballistic missiles in the past. However, air defences are never 100 percent effective. The Israel Defence Forces said they are investigating: “The incident is still being thoroughly examined. Some of the conclusions have already been implemented regarding interceptions and alerts. No further details regarding aerial defence activities and the alert system can be given due to information security considerations. We emphasise that aerial defence is not hermetic and the public must follow the Home Front Command instructions.”

The Houthi attacks on Israel have increased and become regular. These include missile attacks that set off sirens across central Israel, sending more than 2 million people to shelters. Israel retaliated for one of the attacks on December 19, striking ports and energy infrastructure in Yemen. This was the third round of retaliatory strikes by Israel. However, these types of strikes may not work to deter the Houthis.

To understand this particular challenge one has to remember that the Houthis burst onto the scene in the Middle East back in 2015. In those days the Obama administration was rushing toward an Iran deal. To get there, the US began to appease Iran in other areas of the region. This meant the US stepped back from threats against the Assad regime. Feeling that the regime had breathing space, Russia intervened in Syria. Iran increased its support for the Houthis in Yemen, Iraqi militias, Hamas, Hezbollah and other groups.

The Houthis in Yemen were an unexpected contribution to Iran’s ongoing attempt to take over the Middle East. They came to control the mountainous area of what was called North Yemen. This area is actually in western Yemen and the mountains around Sana’a. When the Houthis began to march on Aden on the coast, Saudi Arabia led several Arab states to intervene in 2015. This was important for the Saudis. They did not want the hostile Houthis on their border. At first it seemed like Riyadh, Abu Dhabi and others would be successful. However, with Iranian backing the Houthis became resilient. Soon they had new drones and missiles with Iranian backing. They began attacks on Saudi Arabia, including targeting Riyadh.

After several years of an increasingly difficult war in Yemen, the Saudis stepped back and there was a ceasefire. This was in the context of Saudi-Iran reconciliation and the end of the Gulf Crisis that had seen Saudi Arabia and the UAE seek to isolate Qatar in 2017. By the time the Biden administration came into office, the Saudis were moving to have talks with Iran and patch things up with Doha. The Biden administration also removed the Houthis from a list of terrorist groups. The Houthis hadn’t changed, but the Biden administration rewarded them anyway.

The Houthis felt they were on the winning side, and Iran was growing in power. The Houthis decided to use their new found power and clout to knit themselves into the “axis of resistance” with Hezbollah, Hamas and other Iranian-backed groups. The Houthis were already a vicious anti-Israel and antisemitic group with an official slogan of “curse the Jews” and which called for the “death” of Israel. But the rhetoric was not taken seriously enough. Only after the Houthis joined the war on Israel in the wake of the Hamas attack on October 7 did it become clear how powerful they had become.

There had already been hints of the newfound Houthi power. They had based Iranian-style Shahed 136 drones in Yemen in late 2020. These same drones were also provided by Iran to Russia in 2022 when Russia began its war on Ukraine. As such, the Houthis were now knitted into a number of Iranian fronts. They chose to help Hamas by attacking southern Israel with missiles and drones and then also carrying out attacks on shipping. This brought US Central Command and several western powers into the confrontation with the Houthis. However, they have not been deterred. They have carried out hundreds of attacks on shipping and on Israel. They use drones and missiles to attack Israel. They have become increasingly proficient as well. In July a drone flown from Yemen approached Israel from the sea and narrowly missed hitting the US Embassy annex in Tel Aviv before killing an Israeli nearby as the drone exploded.

Israel has retaliated against the Houthis several times. Each of the strikes has been complex. It involves multiple warplanes including F-16s, F-15s and F-35s and also refuellers. Commentators have pointed out that this is good practice for Israel for long range missions. Indeed, Israel has carried out two long range strikes on Iran in retaliation for ballistic missile attacks. In addition, after December 8 when the Assad regime fell from power, Israel carried out hundreds of precision strikes in Syria to destroy the former military assets of the Assad regime, lest they fall into the wrong hands.

Israel has impressive capabilities. The US carrier strike group off the coast of Yemen has impressive capabilities as well. However, airstrikes on ports and various buildings used by the Houthis may not work to deter them. The Houthis grew up in Yemen not in control of ports and power plants but, rather, as a mountain militia. They are used to privation. They don’t likely care much if they lose some empty buildings. Hezbollah also withstood a year of Israel’s airstrikes on “terrorist infrastructure” in southern Lebanon. It wasn’t deterred. Hamas has also survived a year of Israeli operations in Gaza. It doesn’t mind hiding under rubble.

Israel and the US may need to increase the types of strikes on the Houthis if they want the Houthi attacks to stop. The group knows it is some 1,200 miles from Israel. It knows it is difficult for Israel to carry out a sustained campaign in Yemen. It also knows that precision airstrikes don’t win wars. Deterring the Houthis may take time.

Seth J. Frantzman is the senior Middle East analyst for the Jerusalem Post, an adjunct Fellow at The Foundation for Defense of Democracies and author of The October 7 War: Israel’s Battle for Security in Gaza (2024)