The Houthis held their fire for the first four weeks of the war, despite their affiliation with and backing from Iran.

Now, the movement that still holds the Yemeni capital, Sanaa, and the north and other areas of the country, has made its first move, firing missiles towards Israel.

The Houthis say they were targeting "sensitive Israeli military sites".

It is true that the threat the Houthis pose to Israel through its missile fire is far less than that of Iran.

The group fired towards Israel many times in support of Hamas after war erupted in Gaza, following the Hamas-led attacks on Israel on 7 October 2023.

But those attacks - which had come to an end many months ago - did little real damage to Israel.

Where the Houthis pose a much bigger threat is off the coast of Yemen.

As part of their support for Hamas, the group targeted shipping coming through the Bab al-Mandab strait at the southern end of the Red Sea, between Yemen and the Horn of Africa.

Their action then endangered that key commercial maritime route.

Were they to do so again, it would be another big blow to the global economy.

Coupled with Iran's near-closure of the Strait of Hormuz, two of the main strategic waterways in the world for trade and energy supplies could potentially be cut off.

The Houthis could also target energy and military infrastructure in its Gulf Arab neighbours, such as Saudi Arabia and the United Arab Emirates - as it has done before.

When the Houthis carried out such actions before, they faced intense air strikes from the US and Israel, aimed at its leadership and military capacity.

But the Houthis appear to have weathered that. The question now is how far the movement is prepared to go.

When it carried out attacks in support of Hamas and the Palestinians, it received some domestic and regional approbation.

Doing so for Iran may be a different matter.

There is also the issue of Yemen itself, which has been relatively calm for some time after years of turbulence and war.

Deepening military involvement by the Houthis in the war between the US, Israel and Iran could trigger a new outbreak in that internal conflict.

There is little doubt that, if the Houthis do continue - and intensify their attacks - it will mark a new escalation and widening of the war.