United Nations officials warned that the escalating conflict in Yemen has left two-thirds of the population in need of humanitarian aid and the country could face famine this year unless immediate action is taken.U.N. Special Envoy to Yemen Ismail Ould Cheikh Ahmed told the Security Council that the "dangerous" upsurge in airstrikes and fighting is having "tragic consequences for the Yemeni people," with 18.2 million in need of emergency food. Ahmed has been trying to get both sides to agree to a cessation of hostilities and a peace plan that could end the war. It has reportedly called for a national unity government.The deteriorating situation in Yemen is "more tragic as a viable proposal for peace is on the table and within reach of both parties," he said. Ahmed said both sides have reservations, and Hadi has criticized the plan and refused to discuss the proposals. He urged both sides to show "political courage" and compromise.U.N. humanitarian chief Stephen O'Brien warned that "an astounding 10.3 million Yemenis ... require immediate assistance to save or sustain their lives" — and "at least 2 million people need emergency food assistance to survive.""The conflict in Yemen is now the primary driver of the largest food security emergency in the world," O'Brien said. "If there is no immediate action, famine is now a possible scenario for 2017."He said the situation for children "is especially grave" with a child under the age of five dying every 10 minutes of preventable causes.O'Brien said 2.2 million babies, boys and girls "are acutely malnourished, and almost half a million children are suffering from severe acute malnutrition" — a 63 percent increase since late 2015.The Security Council called on all parties "to allow safe, rapid and unhindered access" for food, fuel and medical supplies, noting the "widespread and acute malnutrition on the verge of famine."Yemen, on the southern edge of the Arabian Peninsula, has been in the midst of a civil war since September 2014 when Shiite Houthi rebels swept into the capital of Sanaa and overthrew President Abed-Rabbo Mansour Hadi's internationally recognized government. In March 2015, a Saudi-led coalition of Arab countries began a military campaign against Houthi forces, saying its mission served in part as a counterbalance to Iran's influence with the Houthis following its nuclear deal with world powers.But Yemen's U.N. Ambassador Khaled Alyemany told the council that the government refuses to accept the Houthi "coup d'etat in any way or form." He said "the coup masters" must accept a restoration of "constitutional legitimacy" and Hadi's presidency."Any other initiative or idea will be unacceptable and irrational because it will not bring about peace," Alyemany said. "It will only bring about superficial solutions and the crisis will continue."The Security Council expressed serious concern that without a cease-fire and peace agreement the humanitarian situation could deteriorate. Members called on both sides to renew their commitment to a cessation of hostilities.The country is almost entirely dependent on imports, most of which transit through the Hudaydah port, which was bombed by the coalition in 2015. O'Brien said the Saudi-led coalition had ordered a vessel carrying four mobile cranes for the port to leave Yemeni waters and it was now awaiting approval from Riyadh to deliver the new equipment. The cranes will boost the port's capacity to handle humanitarian cargo.The U.N. is calling for a cease-fire in Yemen to allow urgently needed deliveries of humanitarian aid and to resume political talks on ending the war. About 10,000 civilians have died in the war, according to U.N. officials.