The United States has pulled more staff out of its embassy in Yemen, U.S. officials said on Thursday as Washington scrambled to cope with the collapse of a government that had been a key ally in the fight against al Qaeda.

The scaling down of its presence in Yemen is the first sign that the latest turmoil there will affect U.S operations in a country that President Barack Obama hailed just four months ago as a model for “successful” counter-terrorism partnerships.

The U.S. diplomatic contingent in Sanaa was drawn down due to the deteriorating security situation in the Yemeni capital, the officials said. They insisted there were no plans to close the embassy, which could been seen as erosion of U.S. resolve in counter-terrorism operations in the volatile Arab country.

However, current and former U.S. officials say the chaos engulfing Yemen has already threatened the administration’s strategy against a powerful local al Qaeda branch.

Word of the withdrawal of more U.S. personnel came on the day that Yemeni President Abd-Rabbu Mansour Hadi stepped down, throwing the country deeper into chaos days after Iran-backed Houthi rebels battled their way into his presidential palace.

The crisis marks another setback for U.S. Middle East policy when Obama is already struggling with unsteady partners in a campaign against Islamic State militants who have seized swathes of Iraq and Syria. At the same time, Washington seeks to limit Iranian influence in the region.

The Obama administration was caught off guard by the resignation of Hadi, who had backed American strikes against al Qaeda militants. During Obama’s six years in office, U.S. drones have killed hundreds of militants but also dozens of civilians in Yemen, which has stoked public anger in the country.

“We are still assessing the implications,” White House spokesman Josh Earnest told reporters aboard Air Force One.

The State Department had already reduced staff at the embassy in recent months to essential personnel, mostly related to security matters, as the fighters from the Shi’ite Houthi minority seized control of the capital.

"While the Embassy remains open and is continuing to operate, we may continue to re-align resources based on the situation on the ground," a senior State Department official told Reuters. "We will continue to operate as normal, albeit with reduced staff."

INCREASING ALARM IN WASHINGTON

U.S. officials had hoped that Hadi’s announcement on Wednesday that he was ready to make concessions to the Houthi movement would calm the situation but that prospect fell apart just a day later.

Washington is concerned that the chaos in Yemen could create conditions that al Qaeda in the Arabian Peninsula (AQAP) will exploit to strengthen its base of support there and use the country to plot attacks on Western interests. AQAP claimed responsibility for deadly attacks in Paris early this month.

The events in Yemen will "absolutely" limit U.S. drone strikes and counter-terrorism operations in the country in the short-term, a former senior U.S. official said. The official added that if the Houthis ends up in full control of the government they will demand a halt to the drone campaign.

“They hate al Qaeda," said the official, referring to the Houthis. "But they also hate the United States.”

Some U.S. officials believe that while the Houthis are determined to wield more power in Yemen the movement may not want to assume responsibility for actually governing the divided, impoverished country.

But overall the Obama administration appears to have few contacts with the Houthis and remains concerned that their emergence as the country’s main powerbrokers will mean greater influence for Shi’ite Iran in Yemen’s affairs, a prospect that also worries neighboring Sunni power Saudi Arabia.

U.S. officials say Iran has backed the Houthi rebellion with financial and political support and that shipments of Iranian weapons have also been found destined for the group.

Senator John McCain, chairman of the Armed Services Committee and a frequent Obama critic, said events in Yemen reflected misguided U.S. policy and called for a full evacuation of the embassy there. Obama’s earlier hailing of Yemen as a counter-terrorism success, he added, showed the president “is either delusional or misinformed.”

The crisis poses another major challenge to Obama's efforts to close the U.S. military prison at Guantanamo Bay, Cuba.

A U.S. official said Washington had no intention of repatriating any of the nearly four dozen Yemeni detainees already approved for transfer from the internationally condemned jail while the security situation remains unstable in Yemen.

Obama lifted an moratorium on sending Yemenis home nearly two years ago and has no plans to reinstate it, the official said. But he has yet to send a single Yemeni home from Guantanamo since ending the ban, instead transferring a handful for resettlement in other countries.

Reuters