But Republican lawmakers quickly blasted the proposal as weakening the US military in the face of China's strong defense push, and demanded a larger budget.

For fiscal 2022, which starts October 1 this year, Biden asked Congress to allot a total of $753 billion for defense and national security.

Of that $715 billion would go to the Pentagon, up from $704 billion budgeted for the current year but a slight fall when measured in real terms after inflation.

Biden's budget supports expansion of the US Navy's fleet, amid concerns of it being outpaced by rival China, which the Defense Department considers its primary challenge.

Biden is also proposing to modernize the country's nuclear weaponry and strengthen the delivery systems -- bombers, submarines and missiles.

Nearly $107 billion would go to weapons- and defense-related research and development, the highest level ever, with a growing focus on hypersonic missiles, artificial intelligence, microelectronics and autonomous vehicles.

But it also places an emphasis on military operations that acknowledge and address climate change.

"It is vital to national security that US military installations, and the mission critical capabilities these installations support, are resilient to climate-induced extreme weather," the White House said in its spending proposal.

- 'Wasteful projects' -

In addition, the US armed forces will get a modest pay increase under Biden's proposal.

The budget "continues to improve military readiness and invest in the modernization of a more lethal force," the Pentagon said in a statement.

Trump sharply pushed up the Pentagon budget beginning in fiscal 2018 after years of tight controls due to the lengthy recovery from the 2008 financial crisis.

The initial budget proposal is mostly a wish list and the administration will have to hash out details with Congress beginning around mid-year, in a process that can increase or reduce the final budget.

In a statement, Senate Republican leader Mitch McConnell along with other Republican senators, blasted Biden's proposal as sending a "terrible signal" to adversaries and allies alike.

"China's military investments match its desire to out-compete America and hold our military forces at risk. President Biden's defense spending cut doesn't even keep up with inflation," they said.

"Talk is cheap, but defending our country is not," they said.

Progressive Democrats in Congress said Biden needs to make real cuts to military spending after Trump's increases.

Representative Ro Khanna questioned the plan to put more than $100 billion into a new generation of land-based intercontinental ballistic missiles, part of the country's nuclear defense force.

The US should not be "pouring more money into price gouging defense contractors and wasteful projects," he said on Twitter.