U.S. drone strikes killed at least eight suspected al- Qaeda militants in Yemen on Thursday, bringing the number of people killed by drones in less than two weeks to at least 25.

The strikes follow Yemen’s announcement on Wednesday that it had foiled a plot by al Qaeda to seize two major oil and gas export terminals and a provincial capital in the east of the country.

Warnings of potential attacks have pushed Washington to shut missions across the Middle East, and the United States and Britain to evacuate staff from Yemen.

Witnesses and local officials in Maareb, a mostly desert region in the southeast, where militants have taken refuge, said a drone fired at two vehicles suspected of carrying al-Qaeda militants at dawn, killing six people.

Residents saw the two vehicles rise in flames and the drone circled the air for a while after the attack.

Another two were killed in the eastern region of Hadramout, local officials said.

At least 25 suspected militants have been killed since July 28, when a drone strike killed at least four members of Ansar al-Sharia, a local militant group affiliated to al-Qaeda in the Arabian Peninsula (AQAP), one of the most active branches of the network founded by Osama bin Laden.

More violence took place in northern Yemen also on Thursday, when five Salafis, followers of puritanical Sunni Islam, were killed in an ambush by Shia’s.

The attack occurred in Saada, a town near the border with Saudi Arabia about 130 km (80 miles) north of the capital, Sanaa. Saada has been under the control of Shia Houthi rebels for several years.

The five Salafis were driving a vehicle when they came under fire in an ambush, which injured a further two, Serour al Wadei, a spokesperson for the Salafi group in Saada, told Reuters.

Houthi Shia rebels led an uprising based in the northern Saada province that Yemeni forces struggled to crush. Saudi Arabia’s military intervened in 2009 before a ceasefire took hold the next year.

Yemen, one of the poorest Arab countries, is one of handful of countries where Washington acknowledges targeting militants with strikes by drone aircraft, although it does not comment publicly on the practice.

U.S. sources have told Reuters that intercepted communication between bin Laden’s successor as al-Qaeda leader, Ayman al-Zawahri, and AQAP was one part of the intelligence behind the alert last week that prompted the closure of the embassies.

Security in Yemen is a global concern. Home to AQAP, considered one of the most aggressive branches of the global militant organization, it shares a long border with Saudi Arabia, a U.S. ally and the world’s top oil exporter.

The U.S. government supports Yemeni forces with funds and logistical support.

Yemeni authorities issued a statement early on Tuesday, listing 25 “most wanted terrorists” it said were planning to carry out attacks in the country during the Muslim Eid al-Fitr holiday, which started Thursday. They offered a five million Yemeni riyals ($23,000) bounty for information leading to their capture.  

— Reuters