US President Donald Trump vowed on Sunday to veto this year's defense budget bill, this time citing unspecified claims that it could potentially benefit China.

"The biggest winner of our new defense bill is China! I will veto!'' Trump wrote in a new tweet.

He's threatened to reject the annual bill before, despite Congress passing the bill by margins that would allow lawmakers to override the president's veto.

The legislation passed the Republican-led Senate by 84-13, while it passed the Democrat-controlled House of Representatives by 335-78.

The votes put the bill — the National Defense Authorization Act (NDAA) — well beyond the two-third "super majority" needed to override a potential veto by Trump.

The $740.5 billion (€610.2 billion) bill covers the US military's budget for the year and includes pay raises for service members.

In a rare break with Trump, Senate Majority Leader Mitch McConnell urged for the bill to be passed, saying it would help deter Chinese military aggression.

Trump's veto threats also come a little over a month until he is due to leave office, with US President-elect Joe Biden set to be sworn in on January 20.

Why does Trump object to the bill?

Trump has voiced his opposition to the bill for several reasons — including a provision that would require US military to rename bases honoring Confederate leaders from pro-slavery states during the Civil War.

The US president also wants lawmakers to include provisions that are unrelated to military and national defense that would target social media companies. Specifically, Trump wants the bill to abolish a law that protects social media giants from being liable for third-party content.

Trump has regularly claimed that Google, Facebook and other tech giants are biased against him.

The defense bill, which Congress has passed for nearly 60 years in a row, also includes a provision that would block Trump's plan to withdraw thousands of US troops from bases in Germany.

The legislation also includes mandatory sanctions on Turkey for its acquisition of the Russian S-400 air missile defense system.

rs/aw (AP, AFP)