Nearly four out of five children in Yemen are now in need of immediate humanitarian assistance, leading humanitarian groups announced in a joint statement Wednesday. Executive directors from UNICEF, the World Food Programme, and the World Health Organization said the overwhelming majority of Yemen’s children now face a “vicious combination” of indiscriminate famine and the world’s worst cholera epidemic on record.

The crisis forces Yemeni parents to make an impossible choice: seek medical treatment for their sick children or buy food and other essentials to keep their families alive, Joe English, a spokesperson for UNICEF, told VICE News.

“Yemen is suffering the worst humanitarian disaster in its modern history,” English said. “Its children, the most vulnerable of the population, are the biggest victims.”

Over 6.8 million people in Yemen are in a state of emergency, with the number of cholera cases skyrocketing to 400,000, according to latest figures from the United Nations.

Nearly 2,000 people have already died from the outbreak. Oxfam has little hope the outbreak will be contained anytime soon, estimating 600,000 people will have cholera by year’s end.

A child is now infected with cholera every 35 seconds, according to Save the Children, and every 10 minutes a child under 5 in Yemen is dying from preventable causes, according to the U.N.

The latest figures highlight the devastation brought on by the crippling two-year war between Saudi Arabia’s coalition forces and Houthi rebels. The U.N. and human rights groups have blamed both sides for the immense humanitarian toll and the crackdown on civil society, with the Saudi-led coalition responsible for a “disproportionate amount” of civilian casualties.

International donors pledged nearly $1.2 billion in aid in April, but a massive chunk of that aid hasn’t gone through, delayed by a decimated health infrastructure, and hindered access to key transportation points, like the Sanaa airport. The United Nations suspended a program to ship cholera vaccine doses to Yemen in early July, saying that the delivery of the vaccines was too difficult in the midst of warfare.

Global leaders, including Secretary of Defense Jim Mattis, have urged for U.N.- brokered negotiations as a means to end the war in Yemen, but critics say Saudi Arabia (the principle actor) has little incentive to seek a political solution so long as the U.S. and the U.K. continue to provide critical military support to its coalition forces.