US President Donald Trump's budget proposes to boost defence spending by $US54 billion ($70 billion) — the largest increase since Ronald Reagan's military build-up of the 1980s — as well as cut the Environmental Protection Agency's (EPA) funding by 31 per cent.

Key points: "We're not spending money on that," budget director says of climate change programs

"We're not spending money on that," budget director says of climate change programs Rural areas where Donald Trump did well "especially hard hit by budget"

Rural areas where Donald Trump did well "especially hard hit by budget" Mr Trump has vowed not to cut social security, Medicare

The $US1.15 trillion budget blueprint, submitted to Congress on Thursday, calls for cuts to housing assistance and community programs such as Meals on Wheels, a move Mr Trump's budget director called "fairly compassionate", especially for those people "giving us the money".

Deep cuts elsewhere — to the environment, agriculture, and the arts — are being presented as a necessity in order to fund a military build-up aimed at tackling the Islamic State (IS) group and other threats.

"To keep Americans safe, we have made the tough choices that have been put off for too long," Mr Trump declared in a statement titled America First that accompanied the budget.

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Budget director Mick Mulvaney said it was "a hard power budget, not a soft power budget".

The proposed cut to the EPA budget is part of the White House's plan to eliminate climate change programs and trim initiatives to protect air and water quality.

More than 3,000 EPA workers would lose their jobs in the biggest cut of any federal agency in the 2018 budget.

Budget director Mick Mulvaney said funding to climate change programs was considered "a waste of your money".

"I think the President is fairly straightforward. We're not spending money on that," he said.

However, the budget is not entirely in line with Mr Trump's campaign pledges.

It would make a big down payment on the US-Mexico border wall, which Mr Trump repeatedly promised the Mexicans would pay for — American taxpayers will, at least for now.

Thursday's proposal calls for an immediate $US1.4 billion infusion with an additional $US2.6 billion planned for the 2018 budget year starting on October 1.

'Compassionate' budget cuts

When ask if the cuts to community programs were "hard-hearted" rather than "hard-powered", Mr Mulvaney said he thought it was "probably one of the most compassionate things we can do".

"You're only focusing on half the equation, you're focusing on recipients of the money. We're trying to focus on both the recipients of the money and the folks that give us the money in the first place," he said.

"I think it's fairly compassionate to go to them and say 'look, we're not going to ask you for your hard-earned money anymore'.

"We're not going to do that anymore unless we can guarantee to you that that money is to be used in a proper function."

Rural areas 'badly hurt'

Republicans praised Mr Trump for beefing up the Pentagon, but were less enthusiastic about accepting his recipe for doing so without adding to the nation's $US20 trillion debt.

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"While we support more funding for our military and defence, we must maintain support for our farmers and ranchers," North Dakota Republican John Hoeven said.

The proposed budget would close numerous county offices that help farmers and rural residents navigate farm subsidy and rural development programs.

"If you look at the areas where Donald Trump did especially well, they are especially hard hit by this budget. Rural areas get badly hurt," Senator Chris Van Hollen said.

Mr Mulvaney acknowledged passing the cuts could be an uphill struggle and said the administration would negotiate.

Law enforcement agencies like the FBI would be spared. In addition to the billions for the border wall, there was a request for $US1.2 billion for the current budget year for additional border patrol and immigration control agents.

Budget director Mick Mulvaney said it was "a hard power budget". ( Reuters: Kevin Lamarque )

Trump set against raising taxes

Parts of Mr Trump's spending plan for the next fiscal year angered both congressional Democrats and Republicans who will have the final say on it.

While it targets Democratic priorities like housing, community development and the environment, it also would slash GOP sacred cows like aid to rural schools and subsidised airline services to Mr Trump strongholds, and it would raise fees on participants in the federal flood insurance program.

The budget eliminates the National Endowment for the Arts, legal aid for the poor, low-income heating assistance and the AmeriCorps national service program established by former president Bill Clinton.

Mr Trump's proposal covers only roughly a quarter of the approximately $US4 trillion total federal budget.

This is the discretionary portion Congress passes each year, not addressing taxes, social security, Medicare and Medicaid.

Nor does it make predictions about deficits and the economy.

Those big-picture details are due in May, and are sure to show large, probably permanent, budget deficits.

Mr Trump has vowed not to cut social security and Medicare and is dead set against raising taxes.

AP/Reuters