After months of fighting that has killed thousands of civilians in the impoverished nation, the United Nations announced last week that negotiations over a possible permanent end to hostilities would take place in Switzerland.
The conflict in Yemen pits Houthi rebels, who seized control of the capital at the start of the year, against forces loyal to President Abdu Rabu Mansour Hadi and the Saudi-led coalition of Arab countries that support him.
The Saudis and their predominantly Sunni allies consider the Houthis, who hail from northern Yemen, to be proxies for the Shiite government of Iran.
The Houthis, who follow a different strain of Shiite Islam from the one upheld by the regime in Tehran, deny that Iran supplies them with any direct material support.
Poor track record of ceasefires
A seven-day ceasefire to coincide with the peace negotiations began at noon, local time (4 a.m. ET).
The truce had originally been expected to start four hours earlier, but the Saudi-led coalition said in a statement reported by Saudi state media late Monday that it had been pushed back.
Earlier Monday, two senior officers in the coalition -- one of them Saudi, the other from the United Arab Emirates -- were killed in battle near the southwestern Yemeni city of Taiz, Saudi and Emirati state media reported.
Previous ceasefires in Yemen have fallen apart or only been partially observed, with the warring parties accusing each other of not respecting the terms.
Terror and hunger spread amid conflict
The vicious and protracted conflict in Yemen has allowed the rival terrorist groups al Qaeda in the Arabian Peninsula and ISIS to expand their reach amid the security vacuum.
U.N. agencies have repeatedly warned of an escalating humanitarian crisis as the fighting has deprived millions of people of food supplies.
The peace talks are "the only way to end the suffering of the Yemeni people," the U.N. Special Envoy for Yemen, Ismail Ould Cheikh Ahmed, said last week.