JOHANNESBURG -- The United Nations World Food Program, which relies on the U.S. for nearly half its budget, is closing its Southern Africa bureau due to funding constraints, the agency said on Monday as the region struggles to withstand a severe drought.

President Donald Trump's administration has slashed foreign aid contracts around the world as part of its 'America First' agenda, including funding to life-saving U.N. programs.

The WFP did not quantify how much it would lose from Trump's aid cuts, but regional spokesperson Tomson Phiri said that the donor funding outlook had become "constrained".

The United States is the single largest donor to the WFP - which gives food and cash assistance to people suffering from hunger due to crop shortages, conflict and climate change worldwide - providing $4.5 billion of its $9.8 billion budget last year.

An El Nino-induced drought last year caused Lesotho, Malawi, Zambia, Zimbabwe, and Namibia to declare a national disaster.

The agency would consolidate its eastern and southern African operations and run both from Nairobi, Phiri said.

"The goal is to stretch every dollar and target maximum resources to our frontline teams," he said, adding that the closure would not affect country operations in Southern Africa.

The WFP says that overall, more than 60 percent of the food it procures is used in operations in the region in which it was purchased.

The agency was already short on funding, having raised just one-fifth of what it needed for the drought response last year.

Trump's administration is cutting more than 90 percent of the U.S. Agency for International Development's foreign aid contracts and more than $58 billion in overall U.S. assistance around the world.