The latest round of US bombing against Houthi targets in Yemen comes as little surprise, and raises with it the prospect of an extended military campaign affecting a nation already impoverished by years of war.

The assault implies an effective recognition by Washington that any effort to try to completely halt the attacks on western shipping in the southern Red Sea will require repeated intervention because of the Yemeni group’s capacity and determination to resist.

Since Friday morning’s initial 150 bomb assault by British and American forces – plus a follow-up attack on a radar facility 24 hours later – the Houthi rebels have launched a missile at a US navy destroyer (which was shot down), struck two commercial vessels with missiles, damaging each of them slightly, and aimed a drone at a third, again causing some damage but no injuries.

On Thursday the movement’s leader Abdul-Malik al-Houthi, in his first speech since the US led intervention, said it was “a great honour” to be in direct confrontation with the Israelis, Americans and British, characterising it as part of Houthi attempts to intervene in support of Palestinians in Gaza – a moral cause from which it will be politically difficult to back down.

In narrow military terms it is not a fair fight, although asymmetric conflicts are nothing new. The problem is that the US and their allies have the capacity to keep bombing Houthi targets in Yemen for a long time, while the Houthis still retain the ability to close the southern Red Sea to merchant shipping, and so impose economic costs on the west.

Cargo volumes through the Red Sea were already down by 70% in December according to the Kiel Institute for the World Economy, forcing goods to be diverted around Africa, increasing costs and shipping time by about 10 days, while Lloyd’s List estimated on Monday that 23 merchant ships stopped or reversed in response to last Friday’s wave missile strikes.

Confidence has not returned since. Insurance premiums have tripled in the past week, although some of this is theoretical because maritime underwriters are also reporting a sharp drop in inquiries as oil majors and container operators abandon the most direct seaborne route between Europe and Asia.

In a briefing earlier this week, Pentagon spokesperson Maj Gen Patrick Ryder was vague about the amount of damage the US believes it did to the Houthi’s capacity to launch missiles and drones, declining to endorse leaks to the New York Times suggesting about 25% of the Yemeni group’s attack capability was degraded.

Avoiding such simplistic calculations was almost certainly wise, not least because destroying launch capabilities takes longer than expected. Earlier this week, Hamas, under unremitting Israeli bombardment in Gaza, launched 25 rockets at the southern city of Netivot, using hard to detect launchers buried in the ground. Iranian Shahed drones, of the type used by the Houthis, are designed to be launched from the back of modified trucks, which are easy to move.

The question for the US in particular is how far it is willing to go. It could take many more attacks to stop the defiant Houthis targeting western shipping. But while fighting continues there remains the risk that either side could launch an attack with devastating consequences for Yemeni civilians or American or British sailors – bringing with it further calls for escalation and revenge.

Meanwhile, the real losers will be ordinary Yemenis. This week, Action Against Hunger, an NGO, warned that Yemen is almost entirely dependent on food and medical imports, and that humanitarian groups are finding it increasingly difficult to bring in medicines. It estimated 17 million Yemenis lacked access to food in 2023, while rates of acute malnutrition among women and children in Yemen remain among the highest in the world.