Yemen’s Iran-aligned Houthis launched ballistic missiles and drones at displacement camps and residential neighborhoods in the city of Marib on Friday, killing two people and wounding 14 others, state news agency SABA reported, citing local authorities.

The Houthis said they had targeted Saudi-backed forces, depots, vehicles and military equipment at the Sahn al-Jinn camp in the city with missiles and drones. Reuters could not independently verify the claims by either side.

The attacks came a day after at least 30 Yemeni government troops were killed in strikes on military camps in Marib and Hadramawt provinces, according to government sources, in one of the deadliest escalations in months.

The Houthis also claimed responsibility for Thursday’s attacks, saying they struck Saudi military deployments in the two provinces after detecting what they described as a large Saudi military buildup ahead of an escalation against areas under their control.

U.N. Special Envoy for Yemen Hans Grundberg said on Friday that the latest attacks in Marib and Hadramawt, together with renewed attacks on commercial shipping in the Red Sea and Gulf of Aden, had left Yemen at its greatest risk of renewed large-scale conflict since the U.N.-brokered truce in April 2022.

He urged all sides to exercise maximum restraint and engage in U.N.-led negotiations, warning that the violence risked drawing Yemen deeper into a wider regional confrontation.

The Houthis declared a naval blockade on Saudi Arabia in the Red Sea last month in response to what they described as a Saudi siege of Yemen, an allegation Riyadh denies.

Saudi Arabia has led a military coalition backing Yemen’s internationally recognized government since 2015, after the Houthis seized the capital, Sanaa, in 2014. The war has devastated Yemen and triggered one of the world’s worst humanitarian crises.