A North Korean vehicle carrying a missile passes by during a mass military parade in Pyongyang's Kim Il Sung Square to celebrate 100 years since the birth of the late North Korean founder Kim Il Sung. (Ng Han Guan/AP)

Senior U.S. officials are studying images of mobile missile launchers prominently featured in a North Korean military parade, but there are doubts about whether they even work.

Amid the military hardware known to the U.S. on display during what North Korea dubbed a parade of its "military might" was something new: a massive 16-wheeled vehicle carrying an intercontinental ballistic missile.

The equipment got the immediate attention of U.S. officials, with Defense Secretary Leon Panetta telling a House committee Thursday that Washington has a "growing concern about the mobile capabilities on display in the parade." If the mobile ICBM launcher works, "that increases the threat coming from North Korea," Panetta said.

Lawmakers and analysts speculate Pyongyang got help—or even bought the mobile launcher and missile—from China. Panetta acknowledges U.S. intelligence that suggests Beijing has provided North Korea with such technology before, but said officials have yet to determine whether the mobile launcher is of Chinese origin.

Yet, experts have their doubts about the mobile launcher. In weapons development, like baseball, batting averages matter. And in the area of successful long-range missile launches, North Korea isn't exactly knocking the cover off the ball.

"It seems unlikely that those missiles were actually functional, especially given the long record of failure in their ballistic missile development," says Jan van Tol, a retired Navy captain who advised Pentagon and White House officials.

The Nuclear Threat Initiative, a non-profit group that studies nuclear and biological weapons issues, concludes the "road-mobile ICBM" system will "require more work on staging and solid-fuel technology."

North Korea began work on a Taepodong-2 intercontinental ballistic missile in the mid-1990s, a platform that U.S. officials say has the potential to reach the west coast of the United States.

But the ICBM program was plagued by a "lack of success in its flight testing," according to NTI. In 2006, a Taepodong-2 missile failed about 40 seconds into a test flight, states a NTI fact sheet. Three years later, a modified Taepodong-2 experienced what NTI called a "technical failure" during the first stage of a three-stage test flight, crashing into the Pacific Ocean.

And just last Friday, what Pyongyang insisted was a non-military rocket failed to put a Kwangmyongsong-3 earth observation satellite into orbit. U.S. officials contend what really splashed into the Yellow Sea was a Taepodong-2 missile.

Still, van Tol warns, the U.S., South Korea and their regional allies should not rush to dismiss the North as a paper tiger that never will pose a serious military threat.

"We must not be too contemptuous or amused by the most recent failure, engineers and others can learn a lot from failures," he says. "The U.S. also had a considerable record of failure in the early years of the space program."

The most recent missile launch, and the decision to flaunt the mobile launcher in a parade honoring the 100th birthday of its founder, cannot be overlooked.