UNITED NATIONS — The new U.N. envoy for Yemen said Tuesday a political solution to end the three-year war in the Arab world's poorest country is available — but he warned "there is a real danger" that intensified military confrontations and missile launches "may in a stroke take peace off the table."

Martin Griffiths said in his first briefing to the Security Council that urgent and creative ways must be found "to diminish the chances of these game-changing events, upsetting and derailing the hopes of the great majority of Yemenis."

Houthi Shiite rebels and their allies seized Yemen's capital, Sanaa, in September 2014 and civil war began six months later. A Saudi-led coalition has been trying to restore Yemen's internationally recognized government to power, but the conflict is stalemated, with the Houthis still in control of Sanaa and much of the north.

U.N. humanitarian chief Mark Lowcock told the Security Council Tuesday that Yemen remains "the world's worst humanitarian crisis" with three-quarters of the population — over 22 million people — urgently needing humanitarian help including 8.4 million struggling to find their next meal.

Before the war, Yemen relied on imports for 90 percent of its staple food, medicine and fuel but Lowcock said delays at ports and shortages have led to sharp increases in the price of food and household necessities, forcing hundreds of thousands of destitute families to turn to humanitarian aid to survive.

He said the U.N. World Food Program, which provided aid to 7 million Yemenis in December, is planning to reach 10 million people a month this year.

Last year, an outbreak of cholera and watery diarrhea struck more than a million Yemenis, and Lowcock warned that "unless steps are taken now in high risk districts, we risk another major cholera outbreak."

U.N. envoy Griffiths said "the good news" is that there is a political solution and its outlines are well known: end fighting, withdraw forces, hand over heavy weapons in key locations, and agree on establishing "an inclusive government" that brings all parties together.

"This can be done," he said, but he emphasized that "a successful outcome of negotiations will require patience, diligence and good faith between the parties."

He said he plans to give the Security Council a framework for negotiations within the next two months.

Griffiths said the bad news is that the war has "become louder and more pressing these last few weeks," with an increased number of ballistic missiles launched toward Saudi Arabia, and intensified military operations in Sa'ada governorate in the north.

"The clashes continue without major changes on the front lines, and with disturbing reports of civilian casualties," he said.

Griffiths said the U.N. also hears unconfirmed reports "that movements of forces in Yemen are on the increase" and there soon may be intensive military operations in Al-Hodeida governorate, whose capital is the key port of Hodeida.

"Our concern," Griffiths said, "is that any of these developments may in a stroke, take peace off the table."

U.S. Ambassador Nikki Haley again urged the Security Council to take action to stop the flow of weapons to the Houthis from Iran. Russia and China have not supported this appeal.

Russia's U.N. Ambassador Vassily Nebenzia condemned indiscriminate airstrikes as well as ballistic missile attacks on Saudi soil that target civilians, saying neither help a peace settlement.

He called for a prompt cease-fire and renunciation by the parties to using force and settling their differences militarily.

"This can be done only if there is a focus on Yemen itself rather than attempts to introduce geopolitical calculations into this conflict," Nebenzia said.

He expressed hope that Griffiths will manage "to break the deadlock of this protracted crisis."