US President Donald Trump said Saturday he would like his billionaire advisor Elon Musk to get "more aggressive" in implementing his reform agenda cutting back the federal government.

"Elon is doing a great job, but I would like to see him get more aggressive," Trump wrote on his Truth Social platform. "Remember, we have a country to save."

Trump has put the tech entrepreneur in charge of the Department of Government Efficiency, tasking him with slashing public spending and tackling waste and alleged corruption.

Musk -- the world's richest person and Trump's biggest donor -- has led the effort to fire swaths of the federal workforce.

In the latest cuts announced Friday, the US Defense Department will cut its civilian workforce by at least five percent starting next week.

Trump's administration has already begun firing many other federal workers who are on probationary status.

A judge on Thursday denied a union bid to temporarily halt the firing of thousands of people.

The Department of Government Efficiency (DOGE) is a free-ranging entity run by Musk, though the cost-cutting spree has been met with pushback on several fronts and a mixed bag of court rulings.