The U.N. envoy for Yemen called Friday for the urgent deployment of U.N. monitors to observe the implementation of a cease-fire in the strategic port city of Hodeida and the withdrawal of rival forces — a potential breakthrough in Yemen's four-year civil war.

Martin Griffiths told the Security Council that a speedy presence in the field is "an essential part of the confidence" needed to accompany implementation of Thursday's agreement between Yemen's government and Houthi Shiite rebels reached after eight days of negotiations in Sweden.

Griffiths said in a video briefing from Amman, Jordan that Dutch Maj. Gen. Patrick Cammaert will lead the monitoring mission and could be in the region "as soon as the middle of next week."

While calling the achievements at the talks "a significant step forward," Griffiths also urged caution saying "what's in front of us is a daunting task ... and the hard work is only about to begin."

The conflict in Yemen began with the 2014 takeover of the capital, Sanaa, by Iranian-backed Houthi rebels, who toppled the government of Abed Rabbo Mansour Hadi. A Saudi-led coalition allied with Yemen's internationally recognized government has been fighting the Houthis since 2015.

Saudi-led airstrikes have hit schools, hospitals and wedding parties and killed thousands of Yemeni civilians. The Houthis have fired long-range missiles into Saudi Arabia and targeted vessels in the Red Sea.

The conflict has killed over 10,000 people, created the world's worst humanitarian crisis and brought the country to the brink of famine. Fighting has recently intensified near the port of Hodeida, the "lifeline" for the delivery of 70 percent of Yemen's humanitarian aid and imports including desperately needed food and fuel.

Griffiths said the "ghastly prospect" of famine has made solving the fighting in Hodeida "both urgent and necessary."

The cease-fire agreement in the province of Hodeida, which entered into force upon its publication Thursday, includes "phased but rapid mutual withdrawals from both the three Hodeida ports and the city," he said.

It also gives the U.N. a leading role in managing and carrying out inspections at the ports of Hodeida, Saleef and Ras Issa which must "happen within days," Griffiths said.

The government and the Houthis also reached "a mutual understanding to ease the situation in Taiz" and open humanitarian corridors for people and goods to cross the front lines and reduce fighting in the province, he said.

Looking ahead, Griffiths said both sides agreed to meet again at the end of January and discuss his framework for a political solution to the war that will restore peace to Yemen. He noted that the Houthis "are in agreement with the general tenor of all its elements" while the government has some reservations.

The U.N. envoy responded to people who question whether the parties can be trusted to implement the agreements made in Sweden by saying there are different views.

"My own is that this is not about whether we can trust one or the other on this or that commitment," Griffiths said. "This is about helping them both to make it happen and reporting on their success, and noting those areas where they fall short of that."

He stressed that "verification is the key to building trust."

Griffiths quoted Swedish Foreign Minister Margot Wallstrom who said after Thursday's announcement of the agreements that "no longer can Yemen be considered a forgotten war."

"And now we can begin to hope for a track that may indeed lead to its early resolution," Griffiths added.