The United States has resumed on-the-ground military training aimed at bolstering Yemen’s fight against al-Qaeda, the Pentagon said, following a suspension during a period of intense political upheaval.

“We have begun to reintroduce small numbers of trainers into Yemen,” Pentagon spokesman Captain John Kirby told reporters.

Kirby said the trainers had begun to be sent back to Yemen “recently” but declined to give further details on when that occurred or on the number or location of those trainers.

“We have been working with the government of Yemen and the Yemeni military for some time now to help them deal with the growing threat of al-Qaeda in Yemen,” he said.

The announcement from the Pentagon comes a day after the Obama administration announced what it described as a failed terror plot linked to al-Qaeda’s Yemen-based affiliate.

Officials said militants appeared to be planning to send a suicide bomber, wearing an underwear bomb that was an improved version of one used in a 2009 attempt, onto a U.S- or Western-bound flight.

That alleged plot was the latest manifestation of what the Obama administration believes is a serious threat from al-Qaeda in the Arabian Peninsula (AQAP) in Yemen, a poor, lawless country that has seen mass protests and upheaval in the past year.

Washington backed the power transfer deal under which longtime President Ali Abdullah Saleh, once seen as a vital partner in U.S. counter-terrorism efforts, left office in February.

Kirby said some of the U.S. military support for Yemen’s fight against militancy had been suspended due to unrest there.

While the scale of U.S. on-the-ground activity against al-Qaeda is unknown, U.S. drone attacks continue. Two Yemeni members of al-Qaeda were killed earlier this month by a missile strike that was believed to be fired from a U.S. drone.

Kirby declined to discuss any role the U.S. military might have had in foiling the alleged bomb plot.