President Donald Trump has promised a "historic" increase in the United States' military budget.
Mr Trump said he would propose a budget that would ramp up spending on defence but seek savings elsewhere to pay for it.
He is seeking to boost Pentagon spending by $54bn ($A70.3bn) in his first budget proposal, a rise of around 9 per cent on 2016.
The president will let the Department of Defence decide how to spend the extra billions and most federal agencies will see reductions in funding, an official from the Office of Management and Budget told reporters.
Another White House budget official said he will seek to cut the same amount from non-defence spending, including a large reduction in foreign aid.
"We're going to do more with less and make the government lean and accountable," the president said in a meeting with governors in which he said he planned to propose a substantial increase in public safety spending.
"This budget follows through on my promise on keeping Americans safe," Mr Trump said.
"It will include a historic increase in defence spending."
He told the nation's governors at the White House he will rebuild the "depleted military."
Mr Trump said he is planning to act quickly to bring reforms to the country and emphasising his plans for the military.
He said "we never win - we never win wars" and added that the Middle East is worse off. He told governors: "We have a hornet's nest. It's a mess."
Such a military spending hike would be unusual given that the United States is not engaged in a major war, although its special forces and Air Force are active against Isis in Iraq and Syria.
An official familiar with the proposal told Reuters Mr Trump's request for the Pentagon included more money for shipbuilding, military aircraft and establishing "a more robust presence in key international waterways and choke points" such as the Strait of Hormuz and South China Sea.
That could put Washington at odds with Iran and China.
The United States already has the world's most powerful fighting force and it spends far more than any other country on defence.
Defence spending in the most recent fiscal year was $584 billion, according to the Congressional Budget Office.
Democratic leader Nancy Pelosi, the top Democrat in the House of Representatives, said Trump's plan to slash funding for federal agencies to free up money for the Pentagon shows he is not putting American working families first.
"A $54 billion cut will do far-reaching and long-lasting damage to our ability to meet the needs of the American people and win the jobs of the future," Ms Pelosi said.
"The president is surrendering America's leadership in innovation, education, science and clean energy."
More than 120 retired US generals and admirals urged Congress on Monday to fully fund U.S. diplomacy and foreign aid, saying that "elevating and strengthening diplomacy and development alongside defence are critical to keeping America safe."
Mr Trump has previously said he would expand the Army to 540,000 active-duty troops from its current 480,000, increase the Marine Corps from 23 to 36 battalions - or as many as 10,000 more Marines - boost the Navy from 276 to 350 ships and submarines, and raise the number of Air Force tactical aircraft from 1,100 to 1,200.
But he has not said where he would place the extra hardware and forces or made clear what they will be used for. The United States has been shutting some of its military bases in recent years.
President Trump also told governors that the country will "do more with less and make the government lean and accountable to the people."
But he promised them his budget will increase spending for federal law enforcement, moves that will help the US "fight crime."
He said his budget proposal will also keep tax dollars in the US to help veterans and first responders.
Mr Trump said he would talk about his plans for infrastructure spending in a speech to Congress on Tuesday.
"We're going to start spending on infrastructure big," he said.
"We have to start winning wars again - when I was young, in high school and college, people used to say we never lost a war. We need to win or don't fight it all. It's a mess like you have never seen before."
His budget, once finalised and sent to Congress in mid-March, will likely set off a huge battle in Washington.
Democrats and some Republicans are certain to resist the cuts to domestic agencies, and any legislation to implement them would have to overcome a filibuster threat by Senate Democrats. A government shutdown is a real possibility.
On Friday, Mr Trump told the American Conservative Union's annual Conservative Political Action Conference in Maryland: "Nobody is going to mess with us. Nobody.
"It will be one of the greatest military build-ups in American history."
But, defence experts have questioned the increase in military spending, when the spend on the State Department and foreign assistance stands at $50 billion per year.
The State Department's budget could be cut by as much as 30 per cent, which would force a major restructuring of the department and elimination of programmes.
However, the Republican chairman of the House of Representatives Armed Services Committee called Mr Trump's defence budget request too low.
"Over the course of the Obama Administration, our military funding was cut 20 per cent while the world grew more dangerous. While we cannot repair all of the damage done by those cuts in a single year, we can and should do more than this level of funding will allow," Representative Mac Thornberry said in a statement.
"The administration will have to make clear which problems facing our military they are choosing not to fix," he said.
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