US President Donald Trump has vetoed the annual defence policy bill, following through on threats to veto a measure that has broad bipartisan support in Congress and potentially setting up the first override vote of his presidency.

The bill affirms pay rises of three per cent for US troops and authorises more than $US740 billion ($A980 billion) in military programs and construction.

Long before issuing the veto on Wednesday (local time), Mr Trump had offered a series of rationales for rejecting it.

He has called for lawmakers to include limits on social media companies he claimed are biased against him – and to strip out language that allows for the renaming of military bases such as Fort Benning and Fort Hood that honour Confederate leaders.

Without going into detail, he has claimed the biggest winner from the defence bill would be China.

In his veto message to the House, Mr Trump cited those objections and stated that the measure “fails to include critical national security measures, includes provisions that fail to respect our veterans and our military’s history, and contradicts efforts by my Administration to put America first in our national security and foreign policy actions. It is a ‘gift’ to China and Russia”.

Both the House and Senate passed the measure by margins large enough to override a veto from the President.

Mr Trump had vetoed eight bills previously, but those vetoes were sustained because supporters did not gain the two-thirds vote needed in each chamber for the bill to become law without Mr Trump’s signature.

In advance of the veto, Senate Majority Leader Mitch McConnell, a Republican, has said the bill would help deter Chinese aggression.

Other GOP backers of the measure, including Senator John Thune of South Dakota, the second-ranking Senate leader, and Rep. Mike Gallagher of Wisconsin, a member of the House Armed Services Committee, have tweeted that the bill would counter threats from countries such as China.

Senator Jack Reed of Rhode Island, the top Democrat on the Senate Armed Services Committee, said Mr Trump’s declaration that China was the biggest winner in the defence bill was false. Mr Reed also noted the shifting explanations Mr Trump had given for the veto.

“President Trump clearly hasn’t read the bill, nor does he understand what’s in it,” Mr Reed said. “There are several bipartisan provisions in here that get tougher on China than the Trump Administration has ever been.”

The measure guides Pentagon policy and cements decisions about troop levels, new weapons systems and military readiness, military personnel policy and other military goals. Many programs can only go into effect if the bill is approved, including military construction.

Mr McConnell, in a rare break with Trump, had urged passage despite Mr Trump’s threat to veto it. Mr McConnell said it was important for Congress to continue its nearly six-decade-long streak of passing the defence policy bill.

-AAP