President Donald Trump examined border wall prototypes in San Diego on Tuesday, saying they would block 99 percent of illegal immigrants from entering the country.

“If you don’t have a wall system, we’re not going to have a country,” said Trump, standing alongside Rodney Scott, the chief U.S. Border Patrol agent for the San Diego sector. “There are a lot of problems in Mexico. They have a lot of problems over there. They have the cartels. … The fact is, if you don’t have a wall system, it would be bedlam, I imagine.”

Scott explained the situation on the ground to the president and showed him a poster with before-and-after pictures showing what the border looked like when the current fencing wasn’t in place.

After viewing the eight prototypes, Trump said a “see-through wall” would be the most effective.

“We have to have some see-through capability. If you don’t have some see-through, it’s a problem,” he said.

A border wall was a key campaign promise for Trump in the 2016 election.

The president was briefed on the ongoing assessment of the eight border wall prototypes to determine which one would most effectively prevent illegal border crossings, according to a White House statement on the president’s briefing with Scott; Homeland Secretary Kirstjen Nielsen; Kevin K. McAleenan, acting commissioner of Customs and Border Patrol; Carla Provost, acting chief of U.S. Border Patrol; and James O’Loughlin, project manager for the U.S. Border Patrol Asset Management Office.

The White House also listed the companies that built the prototypes as Caddell Construction Co. LLC, Montgomery, Alabama; Fisher Sand & Gravel Co. of Tempe, Arizona; Texas Sterling Construction Co. of Houston; W. G. Yates & Sons Construction Co. of Philadelphia, Mississippi; KWR Construction Inc. of Sierra Vista, Arizona; and ELTA North America Inc. of Annapolis Junction, Maryland.

“You guys have done a fantastic job. We’ve determined what to do,” Trump said to the Customs and Border Protection agents. “This way, when we build, we’re not saying, ‘Oh, gee, I wish we did it a different way.’ But if you didn’t have [the border fence], you would have tremendous problems. And even the walls they have now, they’re not holding up now.”

Trump also fired back when asked about criticism from California Gov. Jerry Brown, a Democrat, who has said the money could be spent in better ways than building a wall.

“Governor Brown does a very poor job running California,” Trump said. “They have the highest taxes in the United States. The place is totally out of control. You have sanctuary cities where you have criminals living in the sanctuary cities, and then the mayor of Oakland goes out and notifies when [Immigration and Customs Enforcement] is going in to pick them up. … The governor’s doing a terrible job running the state of California.”

Areas of San Diego have both a wall and a fence along the border.

“We have a lousy wall up here now. But at least it stops 90, 95 percent. When we put up the real wall, we’re going to stop 99 percent, maybe more than that,” Trump said. “But this is what it is now, with not a very good wall. But here it is before, and the people just pouring across.”

The president elaborated further on the shortcomings of the current wall and fencing along the Mexican border in San Diego.

“That’s a fence, a very sturdy fence, but coming up, the first thing I noticed is, look how many holes are in that fence,” he said. “Now they fixed the holes, but it doesn’t look very good. They just patch it with more fence.”

“If you take a look at the fence, and it’s a very powerful fence, it’s not doing the trick because they cut holes in it, and they’re patching holes all the time. I’m looking at hundreds of holes cut up and patched. So the fence is not strong enough,” he said.