North Korea claimed it successfully tested a hydrogen bomb on Wednesday, Jan. 6, stoking increasing fears of the country's progress in developing nuclear weapons capable of reaching the mainland United States.
But there's no need to crawl into an underground nuclear bunker just yet.
Though its testing claim has yet to be verified (the White House says North Korea is bluffing), even if North Korea did develop a hydrogen bomb, just building a nuke is not enough to successfully strike a target.
The more important matter is in building a delivery system — a missile — that is capable of launching and safely guiding the nuke to its final destination.
And North Korea has a very rocky history with its long-range delivery systems, which are mostly based on old Soviet technology.
The Hermit Kingdom does have about 1,000 medium-range ballistic missiles capable of striking anywhere in South Korea and most of Japan. But when it comes to long-range intercontinental ballistic missiles (ICBM), which could fly thousands of miles and reach the US, many more hurdles remain.
"Such a weapon would represent more of a political statement than an operational capability since it would suffer from potentially significant problems," reads an April 2015 report on North Korea's Nuclear Futures, written by researchers at Johns Hopkins School of Advanced International Studies (SAIS).
Among the problems researchers laid out for North Korean ICBMs were their low reliability and high percentage of failure: Three out of four tests have flopped thus far. And since the missiles would likely need to be launched above-ground, not from an underground silo, any nuclear-tipped ICBM would be highly vulnerable to a preemptive strike.
Still, even if North Korea were able to launch a nuke using its (so far unsuccessfully tested) Taepodong-2 ICBM, which has the range to hit a place like Los Angeles, it still needs the ability to reenter the atmosphere when it gets there.
SAIS researchers say in their report that it would likely use "a crude and highly-inaccurate blunt body reentry vehicle" similar to 1950s-era nuclear missiles, which would be highly susceptible to US missile defenses.
Still, some experts believe it's less about whether North Korea will develop better nukes, but when.
"This is only a question of time," Mike Gruntman, a rocket scientist and professor of aeronautics at the University of Southern California, told Tech Insider in an email on Wednesday.
"What matters in my view is that they show continuous progress — which means they do not execute their scientists and engineers for failures and let them learn from mistakes," Gruntman said previously, in 2013. "Consequently, the threat is serious and real and should not, in my view, be played down."
For now, North Korea still needs to do a few things it hasn't yet figured out: Get a long-range missile off the ground, and figure out how to get it to strike a target really far away.
"They [now have] essential basics in ballistic missile design, engines, control, structures, and now also nuclear weapons," Gruntman said on Wednesday. "It is a question of methodically advancing the technology. Poor totalitarian countries can concentrate resources even if the population has to starve."
