Yemeni supporters of the Shiite Houthi movement take part in a rally in Sanaa on Wednesday. (Mohammed Huwais/AFP/Getty Images)

The closure of the U.S. Embassy in Yemen has forced the CIA to significantly scale back its counterterrorism presence in the country, according to current and former U.S. officials, who said the evacuation represents a major setback in operations against al-Qaeda’s most dangerous affiliate.

The spy agency has pulled dozens of operatives, analysts and other staffers from Yemen as part of a broader extraction of roughly 200 Americans who had been based at the embassy in Sanaa, officials said. Among those removed were senior officers who worked closely with Yemen’s intelligence and security services to target al-Qaeda operatives and disrupt terrorism plots often aimed at the United States.

The departures were triggered by mounting concerns over security in Yemen’s capital, Sanaa, where Houthi rebels have effectively toppled the government. Britain and France said Wednesday that they also would close their embassies, as news footage showed Houthi fighters driving off in vehicles that U.S. diplomats had abandoned at an airport during their exodus.

The collapse of Yemen’s government had already disrupted some U.S. counterterrorism operations in Yemen. The closure of the U.S. mission compounds the challenges and “is extremely damaging” to the CIA’s mission in Yemen, said a former senior U.S. official involved in the effort. That person said that the embassy had served as the primary base in Yemen for U.S. intelligence operations and that “the political turmoil in Sanaa and the closure of the embassy all play into the hands” of al-Qaeda in the Arabian Peninsula, or AQAP, as the Yemeni franchise is known.

U.S. officials emphasized that not all CIA personnel were withdrawn from Yemen, saying that the agency would try to salvage an intelligence network that it had assembled in cooperation with Yemen, Saudi Arabia and other allies over the past five years.

White House press secretary Josh Earnest said the U.S. continues to coordinate national security efforts with officials in Yemen, despite the decision to relocate embassy staff and operations there. (AP)

But officials acknowledged that key intelligence arrangements and relationships have been at least temporarily severed. The embassy’s closure, for example, involved the departure of key CIA and U.S. military personnel who in recent years have worked alongside Yemeni and Saudi counterparts at a counterterrorism center in Sanaa.

The CIA declined to comment. Senior U.S. lawmakers warned of significant damage to counterterrorism efforts.

“The coup in Yemen and the deteriorating security situation in Sanaa are particularly concerning because they will hinder the United States’ campaign against al-Qaeda in the Arabian Peninsula,” Rep. Devin Nunes (R-Calif.), the chairman of the House Intelligence Committee, said Wednesday in a written statement. “AQAP is a direct threat to the U.S. homeland that we must continue to hunt down with unrelenting persistence.”

The al-Qaeda affiliate in Yemen has been linked to a series of bombing plots targeting the United States, including the failed attempt to blow up a Detroit-bound airliner on Christmas Day in 2009. More recently, the group claimed responsibility for last month’s terrorist attacks in Paris — although whether it was directly involved in the coordination of those assaults remains unclear.

The CIA has deployed teams of operatives and analysts to Yemen, and built an air base in Saudi Arabia for a fleet of armed drones that have carried out dozens of strikes against AQAP targets.

But that campaign has depended heavily on intelligence from informant networks and other sources developed in collaboration with Yemen’s government. The CIA worked particularly closely with Yemen’s primary intelligence services, the National Security Bureau and the Political Security Organization.

The CIA may still be in contact with officials at those agencies, many of whom have continued to report to work despite the chaos in the capital. And three CIA drone strikes in recent days showed that the agency’s aircraft are still tracking AQAP, even if they are no longer doing so with the permission of Yemen’s government.

But the embassy closure has made close coordination with Yemen’s intelligence service all but impossible, prompting worries among U.S. officials that the intelligence streams that have sustained the drone campaign could soon evaporate.

“The issue would be whether you have the intelligence you need to know what to target,” a senior U.S. official said in an interview before the embassy was closed. “To a large extent, that was a product of the cooperation we got from the Yemenis.”

Pentagon officials have said that U.S. Special Operations teams are still in Yemen and continuing to work with that country’s counterterrorism units outside the capital. But U.S. officials acknowledged that those operations also have been impaired by the political turmoil and said that any deterioration in intelligence would also affect a parallel drone program in Yemen operated by the U.S. military’s Joint Special Operations Command.

As recently as September, President Obama described the Yemen arrangements as a model for his administration’s approach to counterterrorism. But the relationship unraveled in recent weeks as Houthi fighters backed by Iran toppled Yemen’s government, dissolved its parliament and put the former president, Abed Rabbo Mansour Hadi, a staunch U.S. ally, under house arrest.

Members of a Shiite sect in Yemen’s northernmost provinces, the Houthis are openly hostile to both al-Qaeda and the United States, although senior members of the group signaled in interviews this week a willingness to consider limited counterterrorism cooperation.

Abdulmalek al-Ajri, a member of the Houthis’ political bureau, described U.S. drone strikes as a violation of Yemeni sovereignty but said the group has not ordered the nation’s intelligence services to halt counterterrorism coordination with the United States or demanded that the drone flights stop. Instead, he said those decisions would be left to revolutionary committees that the Houthis have formed in recent days to assume control of the government.

“If the Americans were to change their strategy and show respect for Yemen’s sovereignty, we would not oppose the drones,” Ajri said, although it was not clear how the United States might meet that standard.

Another Houthi political leader, Deif Allah al-Shami, expressed a similar view, saying that the group is “moving towards fighting al-Qaeda, and if there is anything that can help Yemen while preserving its sovereignty and integrity, then we will take it into consideration.”

In cities outside the capital, tens of thousands of Yemenis took part in demonstrations against the Houthis, who are part of the country’s Shiite minority. At the same time, Houthi supporters rallied in neighborhoods in Sanaa, some waving placards bearing the slogan: “Death to America, death to Israel, damnation to the Jews.”

The State Department said that diplomats and other U.S. Embassy staffers left Yemen on private jets provided by Oman, flying to the Omani capital, Muscat, before traveling Wednesday to Washington. State Department spokeswoman Jen Psaki said that operations at the embassy were “suspended” rather than terminated and that the mission would be reopened when the security situation permitted.

Psaki described the Houthi seizure of U.S. vehicles left at the airport as “unacceptable” and said that “we are requesting their return.” Houthi officials confirmed that the group had taken as many as 20 vehicles left by departing U.S. diplomats, including the ambassador, but indicated that they would be returned to remaining Yemeni staff at the U.S. Embassy on Wednesday evening, with a U.N. official observing the handover.

News footage from Sanaa also showed abandoned weapons at the U.S. diplomatic compound. A U.S. military spokesman said that all weapons left at the embassy or airport had been destroyed or rendered inoperable.

Naylor reported from Sanaa. Karen DeYoung and Missy Ryan in Washington contributed to this report.