Yemen's Houthi rebels claimed Monday they shot down another American-made MQ-9 Reaper drone over the country, with videos purportedly showing a surface-to-air missile striking it. The U.S. military did not immediately acknowledge losing any aircraft.

The strike on power stations and a seaport, which killed four people, was the second known time that Israel has retaliated against the militant group’ attacks by striking in Yemen.

Israel said it struck Houthi targets in Yemen in response to the militants’ recent attacks, and is continuing to carry out strikes on Hezbollah targets in Lebanon. Meanwhile, the number of people displaced by the conflict from southern Lebanon has more than doubled and now stands at more than 211,000, according to the United Nations.