North KoreaCan the U.S. defend itself against North Korean missiles?

North Korea has been making steady progress on three fronts: mastering the building of ever-larger nuclear devices; miniaturizing these devices; and improving the range and precision of its ballistic missiles.

The underground nuclear test North Korea conducted on Sunday was in the range of 50-120 kilotons – that is, 4-to-10 times the size of the bomb the United States dropped on Hiroshima (14.5 kilotons).

There are two questions which cannot yet be answered: 1) Was the nuclear device tested on a Sunday a hydrogen bomb, or a boosted atomic bomb? 2) Was it small enough to fit on a ballistic missile?

North Korea boasted that the answer was “Yes” to both questions, but the country’s leader have embellished they scientific and military achievements in the past.

The trouble is, their embellishments have proven to be mere premature exaggerations, not complete falsehoods: Typically, within months, North Korea proved it was able to perform it boasted about.

Thus, regardless of the specifics of the Sunday test, one thing is clear: North Korea will achieve — within months, not years, and if it has not achieved this already – the capability to deliver a nuclear weapon to the continental United States and detonate it over a major American city.

Does the United States have the means to protect itself against a North Korean nuclear attack?

Since 1983, when President Ronald Reagan announced his Star Wars initiative – the goal of which, Reagan said, was to make nuclear weapons “impotent and obsolete” — the United States has invested vast amounts of money rying to develop a ballistic missile defense. The original idea, advanced by Edward Teller, was to have small nuclear explosions in space to generate laser beams which would zap Soviet missiles as they left their silos on their way to the United States.

Teller’s idea and its permutations were abandoned as impractical, but more traditional kinetic methods of shooting down enemy missiles early in their flight pattern proved more promising.

The BBC notes that the reliability of the anti-missile systems deployed by the U.S. military is not high, especially if the system has to deal with many enemy missiles being launched at the same time.

Proponents of the missile defense notes that North Korea and Iran, the two countries which are likely to pose the most acute threat to the United States, are not going to have large fleets of missiles for long time to come, so that the problem the U.S. ballistic missile defense would have to deal with will be easier than trying to protect the United States against Soviet or Russian missile launch.

Experts also note the success Israel has had in the 2014 war with Hamas, when practically every missile Hamas launched against Israeli city was intercepted by Israel’s Iron Dome system.

This is an important point: Iron Dome was so successful because the system’s sophisticated radars and computers were able to calculate, within 6-12 seconds of launch, which Hamas missile was heading toward a populated area, and which missile was heading toward an empty field. The Iron Dome interceptors went after only those missiles heading toward urban areas.

Israel could afford to make this distinction because Hamas missiles were carrying relatively small conventional warheads. If a missile heading toward Israel was a carrying a nuclear bomb – even if only a Hiroshima-size bomb – it would have been extremely damaging even if it were allowed to explode in an empty field 500 yards from a populated area.

This is why Israel has developed additional layers of ballistic missile defense – called Magic Wand and David’ Sling — aiming to intercept Iranian missiles at great heights and long distances away from Israel.

Critics of the U.S. ballistic missile defense system say that the U.S. system are up to the job. The results of successive tests have been mixed at best – and critics say that the tests are conducted under highly stylized conditions which do not resemble real-world conditions.

The effectiveness of U.S. defensive systems would be enhanced if the United States were to degrade the North Korean launch capabilities through a pre-emptive strike against North Korea’s missile fields and those mobile launchers identified by U.S. satellites. Even if this pre-emptive strike destroyed only 70-80 percent of North Korea’s launchers, the task for U.S. anti-missile defense would become easier.

Such a pre-emptive strike, however, would likely lead to an all-out retaliatory strike by North Korea against South Korea’s urban centers, with the number of civilian casualties reaching hundreds of thousands, if not more.

If the United States abstained from a pre-emptive strike, then the burden on the U.S. anti-missile systems would increase dramatically.