On Twitter Tuesday night, Trump addressed Section 230 of the 1996 Communications Decency Act, which shields companies that can host trillions of information from being sued into obscurity by anyone who feels falsified by something someone else has shared- whether their charge is true or not.
"Section 230, which is a liability shielding gift from the U.S. to 'Big Tech' (the only companies in America that have it - corporate welfare!), is a serious threat to our National Security & Election Integrity. Our Country can never be safe & secure if we allow it to stand," Trump tweeted.
"Therefore, if the very dangerous & unfair Section 230 is not completely terminated as part of the National Defense Authorization Act (NDAA), I will be forced to unequivocally VETO the Bill when sent to the very beautiful Resolute desk. Take back America NOW. Thank you!" he added in another tweet.
Trump has been battling against social media companies for months, asserting they are prejudiced against conservative voices.
In October he signed an executive order instructing executive branch agencies to ask autonomous rule-making agencies, including the Federal Communications Commission and the Federal Trade Commission, to examine whether they can place new directions on the companies.
Since his alleged defeat in the presidential election, Trump has taken to social media his assertions of fraud.
Twitter has tagged many such Trump tweets with the advisory: "This claim about election fraud is disputed."
Tuesday's veto threat is another possible hindrance for the approval of the annual defense policy measure, which is already being held up in Congress by a dispute over military bases named for Confederate officers.
The bill, which has passed for 59 years in a row on a bipartisan basis, guides Pentagon policy and cement decisions about troop levels, new weapons systems and military readiness, military personnel policy, and other military goals.
The sweeping NDAA sets a course for the Department of Defense. It is one of the few major pieces of law seen as a "must-pass" because it dictates everything from pay raises for the troops to how many aircraft should be bought or how properly to compete with rivals like Russia and China.
Before Tuesday night, Trump had previously called for Section 230 to be stopped.
"For purposes of National Security, Section 230 must be immediately terminated!!!" the president wrote on Thanksgiving day.