North Korea's Missile Threats to US May Not Be Empty for Long

North Korea has always talked the talk, and now it seems to be walking the walk as never before.

The nuclear-armed rogue nation appears to be making progress on an intercontinental ballistic missile (ICBM), which could conceivably allow the Hermit Kingdom to make good on its oft-repeated threat to turn major American cities into "seas of fire," experts say.

"They've probably reached the point where they're going to need to start testing the missiles themselves — the whole system," said Joel Wit, senior fellow at the U.S.-Korea Institute (USKI) at Johns Hopkins University's School of Advanced International Studies. "Most people think that could come sometime this year."

Last year's successful test-launch of a missile from a submarine suggests that a mobile-strike capability may be within North Korea's grasp soon as well, analysts have said.

North Korean rocket and missile tech: A brief history

The North Korean missile program got its start with the importation of Soviet Scuds, which made their way into the nation in the 1970s. North Korea reworked Scud technology into a number of variants over the years, apparently with the help of Soviet engineers (many of whom fled the USSR after its 1991 collapse).

These versions include the Hwasong-5 and Hwasong-6, which are thought to have a range of a few hundred miles, and the Nodong, which experts believe can reach targets 620 miles to 800 miles (1,000 to 1,300 kilometers) away. (It's hard to know anything for sure about North Korea's missiles and rockets, because the nation's government is extremely secretive and works to keep much information from getting to the outside world.)

North Korea has also developed longer-range missiles, including the Taepodong-1, Musudan and Taepodong-2, which have estimated maximum ranges of about 1,500 miles (2,500 km), 2,000 miles (3,200 km) and 3,000 miles to 5,400 miles (5,000 to 9,000 km), respectively.

Taepodong-1 has just one known flight under its belt. In April 1998, a modified space-launch configuration of the vehicle lifted off with a small satellite onboard; Western observers concluded that the launch failed.

The Taepodong-2 failed during a 2006 test flight, its only known liftoff. However, North Korea modified the missile into the Unha space launcher, which lofted satellites to orbit in December 2012 and February 2016.

The Musudan has seen a lot more action. North Korea apparently tested the medium-range missile seven times last year, with just one success, said physicist and missile-technology expert David Wright, co-director of the Union of Concerned Scientists' Global Security Program.

Such flights flout United Nations resolutions, which prohibit North Korea from testing missiles and nuclear weapons. Pyongyang has also conducted five known nuclear tests, with the latest one coming in September 2016.