(AP|Getty Images)

In the wake of Friday's fence-jumping incident, the White House is stepping up security with one of the most basic defenses in its toolkit: a second, shorter fence in front of the existing one.

The new portable fence is about waist high and appears to be linked together with plastic ties.

(Carolyn Kaster/AP Photo)

The permanent fence, the only physical barrier in place until today, stands about eight-feet tall.

(Paul J. Richards/AFP/Getty Images)

The new double barricade comes just four days after an Army veteran scaled the fence and managed to enter the executive mansion with a 3 ½ inch knife.

Following the security breach - which has President Obama "obviously concerned," according to press secretary Josh Earnest - the Secret Service vowed to clamp down on security protocols.