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.

To justify the wall, Trump repeatedly insisted criminals, gang members and drug traffickers were pouring over the border and that only a wall could stop them.

“We have far more people trying to get into our country today than probably ever before,” Trump said.

In fact, arrests for illegal border crossings are at their lowest levels since the 1970s. There were roughly 520,000 arrests for unauthorized border crossings last year, which is about one-third of the 1.6 million arrests that happened in 2000. Since 2014, a high proportion of those crossing have been Central American children and families seeking to make humanitarian claims such as asylum.

The total wall funding will now come to about $8 billion, partially approved by Congress but mostly by Trump alone. That will buy the administration some 234 miles of border wall, a senior administration official told reporters Friday.

The national emergency declaration will allow the Trump administration to use about $3.6 billion from Defense Department construction projects to build the wall, along with another $2.5 billion the department had allocated for counter-drug activities, acting White House chief of staff Mick Mulvaney told reporters.

The Trump administration also plans to take executive action to move about $200 million from the Department of Homeland Security and another $600 million from the Treasury Department’s asset forfeiture account.

None of the money will come from hurricane relief, Mulvaney said.

The DHS funding bill included restrictions on where new border wall could be constructed. Those restrictions won’t apply to the portions built with national emergency money, a senior administration official said.