Africa faces the world's largest humanitarian crisis since 1945, with more than 20 million people facing starvation in South Sudan, Somalia and Nigeria, a UN aid official has said.
David Orr, WFP's Africa spokesman, responded to questions about US president Donald Trump's proposal to cut 10 billion dollars (£8 billion) in foreign aid, said that a reduction in funding to humanitarian agencies working in famine-affected areas will cause untold suffering.
Nearby Yemen also faces grave difficulties, Mr Orr said.
The US is WFP's largest donor and was a founder of the organisation.
Mr Orr said that last year the US contributed more than two billion dollars (£1.6 billion), representing about 24% of WFP's total budget.
He said UN operations in South Sudan, Somalia, Yemen and Nigeria will require more than 5.6 billion dollars (£4.4 billion) this year.
Somalia's president Mohamed Abdullahi Mohamed has said almost half the population is facing acute food shortages and 15% are facing famine now.
Mr Mohamed told the UN Security Council by videolink from Mogadishu that Somalis are resilient and would be the last to ask for help, but drought has spawned a humanitarian crisis that could threaten the country's political and security gains.
The UN said the 864 million dollar (£692 million) UN humanitarian appeal for Somalia is only 31% funded.
Foreign Secretary Boris Johnson visited Somalia last week and presided over the meeting.
He said the country is facing its third famine in 25 years and over six million people - about half the population - need help.