Testifying in front of the House Homeland Security Committee Tuesday, Homeland Security Secretary James Kelly said while a physical barrier is necessary on the U.S. southern border with Mexico, the wall promised by President Trump isn't going to happen everywhere overnight.

"I specifically went down to the most affected part of the border, down around McAllen, specifically went down there to talk to local law enforcement, which I did, the governor was there and to talk to my people on the border - ICE as well as CBP. We're not going to be able to build a wall everywhere, all at once," Kelly said.

"We have walls. There are walls there, parts of walls in strategic places in McAllen on the border. But do we need more walls? They said 'well you know Secretary, we need to extend some walls, we need to fill in some places with physical barriers,' their preference would not be something they couldn't see through, that was a finding for me," Kelly continued. "But they very definitively said 'yes sir, we need a physical barrier backed up by people like us, meaning CBP, and local law enforcement, technology where it's appropriate."

Kelly also detailed the immediate need for long overdue physical barriers on high traffic portions of the border. The Secretary didn't give any details about how much the wall is going to cost or how it will be paid for. Estimated from Congress sit at $12-$15 billion.

"I've been trying to get this done [border wall] done for the past six terms in Congress and I think finally we have the political will to do it, so thank you," Committee Chairman Michael McCaul said.

During an interview with Fox News earlier this week, Kelly said he expects to break ground on the border wall by summer 2017, with a completion date set for 2019.

