It is the first time in his two years in office that Trump has used his presidential veto power to block legislation and comes after a dozen Senate Republicans joined Democrats to rebuke Trump's use of his national emergency power to bypass Congress and fund construction of a border wall.
"I'm very proud to veto it", he added.
Most Republicans who defected did so as a protest vote over the president's methods and their fear about the precedent of executive overreach rather than the underlying debate over whether a border wall is necessary.
"I didn't need the vote because we all knew it would be a veto and they're not going to be able to override".
Trump insists he's on solid legal ground, however.
When a deal to prevent another shutdown did not give him the funding he requested, Trump declared a national emergency, redirecting funds that were allocated for other projects to build the barrier instead.
He called the resolution "dangerous" and "reckless", defending the emergency declaration and saying, "People hate the word invasion, but that's what it is".
Senate Republicans have shown support for amending the National Emergencies Act in an attempt to curtail the power of future emergency declarations.
"It's not appropriate for a president to ask for money, Congress decides what to spend and then the president spends the amount he wants anyway under the National Emergencies Act", said GOP Senator Lamar Alexander shortly before voting to terminate the emergency declaration. The resolution had previously passed the Democrat-controlled House. John Barrasso, who voted against the resolution, said Friday. The dozen senators who went against the White House were Susan Collins of Maine, Lisa Murkowski of Alaska, Roy Blunt of Missouri, Lamar Alexander of Tennessee, Pat Toomey of Pennsylvania, Rand Paul of Kentucky, Rob Portman of Ohio, Marco Rubio of Florida, Jerry Moran of Kansas, Roger Wicker of MS and Mitt Romney and Mike Lee, both of Utah.
On Friday, Barr also said the president's emergency order was "clearly authorized under the law".