Yemen’s warring sides resumed United Nations-backed talks Sunday for a prisoner swap, the world body said, more than three months after they concluded the war’s largest exchange.

The talks in the Jordanian capital Amman between representatives of the internationally recognized government and the Houthi rebels came less than a week after the U.S. designation of the Iranian-backed rebels as a terrorist group went into effect.

The U.N.'s special envoy for Yemen, Martin Griffiths, urged the gathering in Amman to prioritize "the immediate and unconditional release of all sick, wounded, elderly and children detainees as well as all arbitrarily detained civilians, including women.”

The talks in Amman are facilitated by the U.N. and the International Committee of the Red Cross (ICRC), Griffiths’ office said.

In October, the warring sides achieved the largest-ever prisoner swap of the war, releasing more than 1,000 detainees. That followed occasional releases of dozens of prisoners over the past two years, which also served as gestures of good faith, stoking hopes the factions would implement a peace deal struck in 2018 in Sweden.

Yemen’s devastating conflict erupted in 2014 when the Houthis seized the capital, Sanaa, and much of the country’s north. That prompted a U.S.-backed Arab military coalition to intervene months later in a bid to restore the government of Yemeni President Abed Rabu Mansour Hadi to power.

The meeting in Amman came after the U.S. declared the Houthis a "foreign terrorist organization,” a designation that took effect Jan. 19, a day before Joe Biden was inaugurated as president. The U.S. move prompted the U.N. secretary-general and other humanitarian officials to urge Washington to reverse the designation to prevent widespread famine and death in Yemen.

Yemen is in the world’s worst humanitarian crisis. The war has killed more than 112,000 people and wrecked the country’s roads, hospitals, water and electricity networks, as well as other infrastructure.