- If President Trump gets his way

the entire 2,000 mile border with Mexico

would look like this.

Clearly marked, with abarrier that makes it

difficult to cross whileallowing agents to see through.

We're here in the San Diego sector,

where they have just put up a new wall,

which is a vast improvement.

It's 18 feet high,compared to the old wall,

which was six feet.

San Diego Border PatrolChief, Rodney Scott,

says this new wall helps secure the border

more efficiently than ever before.

- We've proven that thewall system works here.

It wasn't overlypolitical a few years ago,

it was just right and wrong, makes sense.

- [Heather] The new structurestretches from the Pacific

to the base of the Otay Mountains.

And, it's actually two, aprimary and secondary fence,

with a law enforcement zone in between.

It's an upgrade on multiplefronts, say agents.

The older wall, which hasn'tbeen completely replaced,

was built from Vietnam era landing mats.

It blocks agents vision, preventing them

from spotting illegalcrossers on the Mexico side.

Agent Fabian Carbajal says,it's been a problem for years.

- They would stage 20 people at a time,

wait for our vehicles to go through.

Somebody would jump over with a power saw,

run to our secondarywall, and just breach it,

make a hole through it.

Would run back, stage back in Mexico,

and just wait and see if theborder patrol would respond.

And then, the group would gothrough and make it north.

- [Heather] Chief Scottdoesn't pretend the new wall

can't be beaten, that's not the point.

He's happy that it simply makes it

more difficult for illegalimmigrants to sneak across.

By slowing them down, Scottcan spread out his agents,

creating a human barrierthat saves time and money,

while also boosting morale.

- Where we've put that in place,

we are able to increase our effectiveness

from about 10% to over 95%.

And, more importantly, we are able

to pull 150 agents out of that area.

And then, redeploy them toother parts of the border.

- But, Scott still faces big challenges.

Despite the sections of new wall,

there are stretches of absolutely no wall.

This is where it startsin the San Diego sector,

just north of Tijuana.

It's part of what makesthis a security nightmare.

More than half of theentire southern border

has no fencing, in theSan Diego sector alone

agents must patrol around 17 miles

with absolutely no barrier.

Even the animals are unafraid.

The day we visited, wespotted a small group

of sheep and goats roamingfreely back and forth

in the area where the wall endsand the open border begins.

Agents do their best to secure the area.

They patrol on horseback or ATVs.

And, use technology likeunderground sensors.

But, they're also up against open spaces

with no electricity, and no cell coverage.

Scott says even locals often don't

understand what's at stake.

- [Rodney] They don'trealize, less than 14 miles

off the coast we have noborder fence whatsoever.

And, anything can cross through here.

And, if anybody thinks thatthe criminal organizations,

and the terrorist organizations,

and even nation statecountries aren't trying

to exploit this crisis right now,

they're fooling themselves.

- [Heather] On top ofthis, Scott is caught up

in a border crisis thatis depleting his force.

Across the southwest border,nearly four in 10 agents

are diverted daily to care for

and transport immigrant families.

- The last 24 hours, I had 140 agents

taken out of patrol duties.

And, they're basically babysitting kids,

they're at hospitals with sick aliens,

they're processing, they're transporting,

they're doing things otherthan patrolling the border.

That's created huge vulnerabilities

to where now oureffectiveness is dropping.

- [Heather] Scott blamesrecent court rulings,

which force him to releasefamilies within 20 days,

for helping to create the border crisis.

And, he's looking to Washington to fix it.

He also hopes congress willsee that for border agents,

a wall isn't just politics,it's critical infrastructure

that slows down illegal immigration,

criminals, and anyone elsenot wanting to come through

a port of entry, or whatScott calls, our front door.

Reporting on the San Diego border,

Heather Sells, CBN News.