The US government's giant humanitarian agency USAID on Tuesday announced it was placing its staff in the United States and around the world on administrative leave as it moved to recall employees from overseas postings.

The agency said in a statement on its website — which reappeared Tuesday after going dark over the weekend — that the staff leave will begin shortly before midnight on February 7. 

The administrative leave will hit "all USAID direct hire personnel... with the exception of designated personnel responsible for mission-critical functions, core leadership and specially designated programs."

"Thank you for your service," the statement read.

The move is part of Trump's — and his billionaire ally Elon Musk's — radical drive to shrink the US government, which has shocked Washington and caused angry protests from Democrats and the human rights community. 

The aid arm of US foreign policy, USAID funds health and emergency programs in around 120 countries, including the world's poorest regions.

It is seen as a vital source of soft power for the United States in its struggle for influence with rivals including China, where Musk has extensive business interests.

Musk has called USAID "a viper's nest of radical-left marxists who hate America" and has vowed to shut it down.

Among other criticisms, which Musk has not substantiated, he claims USAID does "rogue CIA work" and even "funded bioweapon research, including Covid-19, that killed millions of people."

The SpaceX and Tesla CEO — who has massive contracts with the US government and was the biggest financial backer of Trump's campaign -- said he had personally cleared the unprecedented move with the president.

The assault on USAID comes in the context of long-running narratives on the hardline conservative and libertarian wings of the Republican Party that the United States wastes money on foreigners while ignoring Americans.

The agency describes itself as working "to end extreme poverty and promote resilient, democratic societies while advancing our security and prosperity."

As of 2023, the most recent year for which full data was available, the top three recipients of aid from USAID were Ukraine, Ethiopia and Jordan, according to the Congressional Research Service. 

Other top recipients of aid included the Democratic Republic of Congo, Afghanistan, South Sudan, and Syria. 

The scale of USAID's funding for Ukraine is significant, with the war-torn European country receiving more than $16 billion in macroeconomic support, according to US government data.

Founded in 1961, the agency's budget of more than $40 billion is a small drop in the US government's overall annual spending of nearly $7 trillion.

The United States is the world's largest provider of official development assistance, according to the Organization for Economic Cooperation and Development (OECD).