Another "surprise" leaked by U.S. intelligence points to just how much in the dark we've been kept about North Korea's nuclear capabilities.

The revelation that North Korea had miniaturized its nuclear weapons to fit atop an ICBM was a "surprise."  We had been told previously that they were at least a year, perhaps two years, away from having that ability.  Then we were told that some of their ICBMs were not only capable of hitting the west coast of the U.S., but also much of the rest of the country.

Now we discover that our intelligence agencies believe that the re-entry system for North Korea's warheads is sophisticated enough that it could survive the plunge to Earth and threaten the U.S.

The Diplomat:

The U.S. Central Intelligence Agency (CIA) has assessed that North Korea's Hwasong-14/KN20 intercontinental-range ballistic missile (ICBM) test launch on July 28 failed to demonstrate successful atmospheric reentry, The Diplomat has learned. The same assessment, however, notes that North Korea's ICBM reentry vehicles would likely perform adequately if flown on a normal trajectory to continental U.S. targets.

U.S. government sources with knowledge of the confidential CIA assessment released in early August note that the reentry vehicle of the Hwasong-14 ICBM launched out of Mupyong-ni on July 28 did not survive to splashdown in the Sea of Japan. The reentry vehicle likely disintegrated; the assessment cites the high lofted trajectory of the July 28 launch as the primary reason for the reentry vehicle's failure.

The CIA assessment notes that based on the two observed flight tests of the Hwasong-14 to date, North Korea's reentry vehicle technology is likely sufficiently advanced to pose no performance problem should the missile be fired at a minimum energy trajectory. The assessment of the reentry vehicle is supported by analysis of data "gathered from ground, sea, and air-based sensors" by the U.S. National Air and Space Intelligence Center (NASIC), one source told The Diplomat.

A ballistic missile's reentry vehicle contains its explosive payload and must withstand immense structural and temperature pressures during its descent through the earth's atmosphere to its intended target. These physical stresses are exceptionally severe in the case of ICBMs, which fly higher than shorter-range systems and reach speeds several multiples of the speed of sound during descent.

According to a U.S. government source with knowledge of the latest ICBM test, the North Korean ICBM's reentry vehicle on July 28 would have encountered structural stresses in excess of those it would see during a minimum energy trajectory flight toward continental U.S. targets.

The CIA assesses this to be primarily due to the exceptionally high apogee of 3,700 kilometers it reached during the flight; North Korea did this seeking to demonstrate the missile's full range capabilities within the Sea of Japan. Temperature stresses on the RV, meanwhile, would likely last longer during reentry off a minimum energy trajectory flight than they would have during the July 28 flight.

Previous to this assessment, the CIA believed that North Korean warheads did not have this capability.  This complicates any U.S. effort to take out the missiles.  North Korea could employ a "use them or lose them" doctrine – a launch on warning systems that means that if we don't get 100% of the missiles in a pre-emptive attack, a few are likely to get through and devastate its targets.

We had better hope Kim is bluffing about launching missiles to hit off the coast of Guam.  Trump would have no choice but to respond to that direct threat in kind.  Escalation after that would be a foregone conclusion.