Did U.S., Japan Know of N.Korean Nuke Test in Advance?

Both Washington and Tokyo were aware of North Korea's preparations for a fourth nuclear test, according to press reports, although they were officially pretending to be shocked and surprised.

Seoul too has officially claimed to have had no idea that the North's nuclear test preparations were this far advanced. The official line here, at any rate, is that North Korea caught everyone off guard.

But the U.S. not only knew, as most pundits did, that the North had dug a new nuclear test tunnel, but "was aware of test preparation for two weeks and launched drones to get a baseline air sample near the site," according to an unnamed official quoted by NBC News.

"It sampled the air again on Wednesday and will test for traces of tritium that would indicate North Korea has something more than a standard nuclear weapon," it added.

The White House does not believe the North's claim that it successfully tested a hydrogen bomb. In a press briefing, White House Press Secretary Josh Earnest said, "The initial analysis that's been conducted of the events that were reported overnight is not consistent with North Korean claims of a successful hydrogen bomb test."

He added, "There is nothing that's occurred in the last 24 hours that has caused the [U.S.] to change our assessment of North Korea's technical and military capabilities."

The Washington Free Beacon reported with that the State Department was evasive when asked if it had known of the nuclear test in advance. The rightwing website pointed out that State Department spokesman John Kirby only replied, "This kind of activity is not new for the regime."

Japanese media carried similar reports. A U.S. electronic reconnaissance plane flew out of Okinawa about 10 minutes before North Korea tested its bomb, Kyodo News said Wednesday. Immediately after the nuclear test, the Japanese Defense Ministry sent up an aircraft to detect radioactive substances in the air, suggesting that Tokyo was notified by the U.S. in advance.

It seems implausible that the U.S. left Seoul in the dark, but that would leave the mystery why South Korea is so firmly insisting it knew nothing.

In a telephone interview with the Chosun Ilbo, a senior Defense Ministry official said, "Both Korean and American officers jointly analyze video images and signals about the North obtained from U.S. military satellites, reconnaissance aircraft, and high-altitude unmanned surveillance aircraft."

"If they didn't know about it here, then Washington surely didn't know either," he claimed.

U.S. Forces Korea Commander Curtis Scaparrotti has also claimed that he did not know anything about the nuclear test in advance. Scaparrotti doubles as head of Combined Forces Command. In other words he is also nominally responsible for South Korean forces.

But states often try to leave potential enemies in the dark about their intelligence-gathering capabilities, so either claims may be true.