Explainer: Is Yemen finally on the road to peace?

Weeks of UN shuttle diplomacy and Western pressure delivered a breakthrough in Yemen peace efforts when the warring parties last week agreed to cease fighting in a contested Red Sea port city and withdraw forces.

The challenge lies in securing an orderly troop withdrawal from Hodeidah, a lifeline for millions of Yemenis facing starvation, amid deep mistrust among the parties.  At the same time, the United Nations must prepare for critical discussions on a wider truce and a framework for political negotiations to end the conflict.

The nearly four-year-old war, which has killed tens of thousands of people, pits the Iran-aligned Houthi group against other Yemeni factions fighting alongside the Saudi-led coalition trying to restore the government of Abd-Rabbu Mansour Hadi.

The Houthis, who ousted Hadi's administration from the capital Sanaa in 2014, and their coalition foes are due to start implementing the Hodeidah ceasefire on Tuesday.

Coalition leaders Saudi Arabia and the United Arab Emirates are under pressure from Western allies including the United States and Britain, which supply arms and intelligence to the Sunni Muslim alliance, to end the war as Riyadh comes under scrutiny after the murder of Saudi journalist Jamal Khashoggi.

Hodeidah is the main port used to feed Yemen's 30 million people and has been the focus of fighting this year, raising global fears that a full-scale assault could cut off supply lines and lead to mass starvation. The war and the ensuing economic collapse have left 15.9 million people facing severe hunger.

The Houthis currently control the city. Coalition-backed Yemeni forces have massed on the outskirts in an offensive aimed at seizing the seaport. Their aim is to weaken the group by cutting off its main supply line.The alliance, bogged down in military stalemate, also wants to secure the coast along the Red Sea, one of the most important trade routes in the world for oil tankers.

The coalition captured the southern port of Aden in 2015 and a string of ports on the western coast, but the Houthis control most towns and cities in Yemen, including Hodeidah and Sanaa. Analysts say implementing the agreement is important, as any lapse in momentum could be used by the coalition as a justification to resume its offensive on Hodeidah.

By Aziz El Yaakoubi and Mohammed Ghobari