Yemen-based Houthis — the last of Iran-backed groups still fully present in the regional war that began 14 months ago — are slowly escalating attacks on Israel with an eye to avoid full-out retaliation.

The Israeli military said the airstrikes targeted infrastructure that the Houthis have used to bring Iranian weapons and officials into Yemen.

The assault killed at least four people and injured 21 others, the state news agency in Yemen reported. The strikes came after a week of attacks by the Iran-backed militia.