DUBAI, United Arab Emirates (AP) — A fourth Bahraini soldier has died of wounds from an attack earlier this week by Yemen’s Houthi rebels targeted forces patrolling Saudi Arabia’s southern border, the island kingdom said late Friday.

The state-run Bahrain News Agency, citing a military statement, identified the slain soldier as 1st Lt. Hamad Khalifa al-Kubaisi.

Al-Kubaisi “succumbed to the injuries he had suffered as a result of the Houthi act of aggression last Monday, while performing his sacred patriotic duties defending the southern borders of Saudi Arabia,” the statement said.

Yemen’s Iranian-backed Houthi rebels have not claimed the attack. The attack on Monday, which also wounded a number of soldiers, threatened recent progress in winding down Saudi Arabia’s eight-year war against the Houthis.

The Saudi-led military coalition said it had “the right to respond at the appropriate time and place.” However, there has been no such response yet amid efforts to reach a peace deal to end the war. Saudi Arabia also sought to blame “elements” of the Houthis, not the overall power structure of the rebel group.

Yemen’s war began in 2014 when the Houthis swept down from their northern stronghold and seized the capital, Sanaa, along with much of the country’s north. A Saudi-led coalition intervened in 2015 to try to restore the internationally recognized government to power.

The fighting soon devolved into a stalemated proxy war between Saudi Arabia and Iran, causing widespread hunger and misery in Yemen, which even before the conflict had been the Arab world’s poorest country. The war has killed more than 150,000 people, including fighters and civilians, and created one of the world’s worst humanitarian disasters, killing tens of thousands more.

Saudi Arabia and Iran restored diplomatic relations earlier this year in a deal brokered by China. Earlier this month, Saudi Arabia welcomed a Houthi delegation for peace talks, saying the negotiations has “positive results.”

A U.N.-brokered cease-fire largely halted the violence, and Yemen has seen only sporadic clashes since the truce expired nearly a year ago.