Season 7 of  "American Ninja Warrior" continued Monday as the NBC series shifted from Pittsburgh to San Pedro, California, for the last leg of the city finals -- the military finals. More than 30 athletes, all U.S. military veterans, returned to the show to try and punch their ticket to the national finals and Mt. Midoriyama. Only 15 spots were up for grabs, though. Who would advance to Las Vegas?

The road to Mt. Midoriyama would be difficult in San Pedro as contestants faced the quintuple steps, the cargo net, the log runner, the monkey pegs, the I-beam cross and the warped wall, as well as the salmon ladder, the swinging frames, the globe grasper and, finally, the dreaded invisible ladder.

There was no competition for the run of the night in episode 12 -- literally, no competition. Only one athlete managed to complete the difficult San Pedro course and that honor belonged to Dustin McKinney. The 5-foot-2-inch Mt. Midoriyama veteran was eyeing up a return trip to the national finals in what might be his last season on "American Ninja Warrior" before possible deployment. McKinney completed the course in just over 9 minutes and 48 seconds, following a surprisingly quick ascent up the always difficult invisible ladder. 

Watch Dustin McKinney's military finals run below:

Other athletes were not so lucky with the invisible ladder. The challenging obstacle got the best of Matthew Jensen and Ryan Stratis. However, the pair made it more than far enough to both qualify for Las Vegas. 

Stratis, who has competed in every season of "American Ninja Warrior," began the course at a blistering pace, setting his sights on completing the course with a faster time than McKinney. However, the invisible ladder slowed the personal trainer and prevented him from reaching the top. 

Watch Ryan Stratis' military finals run below:

In a testament to the difficulty of the course, former Winter Olympian Preston Griffall made an early exit after being bested by the salmon ladder. However, the athlete was still all smiles after his run.

Watch Preston Grifall's military finals run below:

Meanwhile, fans were very much behind Kyle Durand, a true military hero who had come face to face with dictator Saddam Hussein during his time in Iraq. However, Durand became one of the many victims of the I-beam cross Monday.

Watch Kyle Durand's military finals run below:

In total, 15 athletes qualified for the national finals in Las Vegas including, McKinney, Jensen, and Stratis; Ryan Pietschmann, Justin Gielski, Ahmed Toure, and Jeremy Prather, who all went out on the globe grasper; Christopher Moore, Jeremy Guarino, Van Tran, and Steve Martin, whose runs all ended on the swinging frames; and Caleb Hayre, Griffall, Nathan Tucker, and Benjamin Barrett, who all qualified by making it to the salmon ladder with fast enough times.

Watch Matthew Jensen's military finals run below:

Next week "American Ninja Warrior" will air a "Best Runs of the Season" recap episode before heading to Las Vegas and Mt. Midoriyama for the national finals in September. Will one of the athletes conquer the course and become the first American Ninja Warrior? Fans will have to wait to find out.

"American Ninja Warrior" airs Mondays at 8 p.m. EDT on NBC. A replay of of the San Pedro military finals will air on Esquire Tuesday at 8 p.m. EDT.