US President Donald Trump has defended Elon Musk in the face of mounting criticism and said he expected the billionaire to next uncover billions of dollars of “fraud and abuse” at the Pentagon.

Musk’s efforts heading the Department of Government Efficiency (Doge) have triggered alarm amid fears he is overstepping his authority while gutting agencies and programs and firing staff en masse.

In a Super Bowl interview with Fox News on Sunday (US time), Trump said Musk was “not gaining anything” from the role and was, in fact, “terrific”.

He revealed who the CEO of Tesla and X would target next in his cost-cutting and weeding-out measures.

“I’m going to tell him very soon, like maybe in 24 hours, to go check the Department of Education,” said Trump.

“Then I’m going to go, go to the military. Let’s check the military.

“We’re going to find billions, hundreds of millions of dollars of fraud and abuse.”

The Pentagon’s budget is almost $US1 trillion (($A1.6 trillion) a year.

In December, then-president Joe Biden signed a bill authorising $US895 billion ($A1.4 trillion) in defence spending for the fiscal year ending September 30.

Musk, who the White House says is a special government employee, has been tasked by Trump to lead an effort to slash the size of the US federal workforce.

As part of that initiative, Musk aides have sought access to confidential information in computer systems at various government agencies.

Critics say the efforts are likely illegal, risk exposing classified information and, in practice, are gutting entire agencies without congressional approval.

National security adviser Mike Waltz suggested on Sunday that the Pentagon’s shipbuilding processes could be an area of particular interest for Musk’s Department of Government Efficiency.

“There is plenty to look into in shipbuilding, which is an absolute mess,” Waltz said in an interview on NBC.

Leaders from across the political spectrum have long criticised waste and inefficiency at the Pentagon.

But Democrats and unions say Musk’s Doge lacks the expertise to restructure the Pentagon, and its efforts risk exposing classified programs.

Musk’s companies also hold major contracts with the Pentagon, raising significant conflict of interest concerns.

US judge blocks Musk

Meanwhile, a federal judge temporarily blocked the Doge team from accessing US Department of Treasury systems used to process trillions of dollars in payments.

US District Judge Paul Engelmayer in Manhattan issued the order on Saturday after a coalition of Democratic attorneys-general from 19 US states filed a lawsuit arguing Doge had no legal power to access systems.

The ruling also applied to other political appointees of Trump’s administration.

Hours after it was issued, Musk called it “absolutely insane!” in a post on X.

The billionaire said Treasury and Doge had agreed to require all outgoing government payments to include a rationale in the form of a comment and to have a categorisation code.

Musk also said that a do-not-pay list of entities that should not receive government payments should be updated at least weekly, if not daily.

The changes, Musk said on X, were “obvious and necessary” and being implemented by government employees, and not by anyone from Doge.

The lawsuit said Musk and his team could disrupt federal funding for health clinics, pre-schools, climate initiatives, and other programs, and that Trump could use the information to further his political agenda.

Doge’s access to the system also “poses huge cybersecurity risks that put vast amounts of funding for the States and their residents in peril”, the state attorneys-general said. They sought a temporary restraining order blocking its access.

New York Attorney-General Letitia James, a Democrat whose office is leading the case, welcomed the ruling, saying nobody was above the law and that Americans across the country had been horrified by the Doge team’s unfettered access to their data.

“We knew the Trump administration’s choice to give this access to unauthorised individuals was illegal, and this morning, a federal court agreed,” James said.

“Now, Americans can trust that Musk – the world’s richest man – and his friends will not have free rein over their personal information while our lawsuit proceeds.”

Trump says he spoke to Putin

Trump says he has spoken to Russian President Vladimir Putin by phone about ending the war in Ukraine, the New York Post reports — the first known direct conversation between Putin and a US president in two years.

Trump, who has promised to end the war in Ukraine, but not yet set out in public how he would do so, said last week the war was a bloodbath and his team had had “some very good talks”.

Aaboard Air Force One on Friday, Trump told the Post that he had “better not say” when asked how many times he and Putin had spoken.

“He (Putin) wants to see people stop dying,” Trump said.

The White House did not respond to a request for comment.

Kremlin spokesman Dmitry Peskov told the TASS state news agency “many different communications are emerging”.

“These communications are conducted through different channels,” Peskov said when asked by TASS to comment directly on the US report.

“I personally may not know something, be unaware of something. Therefore, in this case, I can neither confirm nor deny it.”

On June 14, Putin set out his opening terms for an immediate end to the war: Ukraine must drop its NATO ambitions and withdraw its troops from the entirety of the territory of four Ukrainian regions claimed and mostly controlled by Russia.

The Kremlin has repeatedly urged caution over speculation about contacts with the Trump team over a possible peace deal.

Putin last spoke to Biden in February 2022, shortly before Putin ordered thousands of troops into Ukraine.

On Friday, Trump said he would probably meet Ukrainian President Volodymyr Zelensky in coming days to discuss ending the war.

Trump told the New York Post that he had “always had a good relationship with Putin” and that he had a concrete plan to end the war.

“I hope it’s fast,” Trump said.

“Every day people are dying. This war is so bad in Ukraine. I want to end this damn thing.”

-with AAP