President Donald Trump on Friday declared a national emergency at the southern U.S. border in an effort to unilaterally seize funding to begin building his long-promised wall between the U.S. and Mexico.

Trump, who was accompanied by parents of children killed by unauthorized immigrants, said he was declaring the national emergency for “virtual invasion purposes.”

But he also acknowledged another reason: He didn’t want to wait on Congress to approve the funds.

“I could do the wall over a longer period of time ― I didn’t need to do this,” Trump said in a televised speech, even as he contended the situation on the southern border amounted to a national emergency. “But I’d rather do it much faster.”

Trump is also expected to approve Congress’ spending bill, which grants him $1.375 billion for the wall, as opposed to the $5.7 billion he initially demanded. The national emergency declaration gives Trump a chance to reroute other government money to fund the project ― and sets up a legal battle that could tie up the president’s signature project for months or years.