No doubt you've read about the nuclear tests North Korea purports to have completed recently.
Therefore, the most important job in the world right now is the job of the air crew of the USAF's WC-135 Constant Phoenix. It's probably right now on station above the Sea of Japan, as close as they can be to North Korea without being in North Korean airspace. The air sample sensors on the Constant Phoenix can gather radioactive debris clouds in real time. That crew knows, more than anyone else outside of North Korea, what happened.
There's only two of these aircraft in the whole USAF (or so we are told.) Let's hope they've budgeted for a few more.
Airliners.net has an older photo of a now-reclassified WC-135 (i.e. this plane is no longer a Constant Phoenix.)
UPDATE: Found a photo of the WC-135W.
According to a line on Drudge, "samples" taken after North Korea's alleged nuclear test yielded to signs of anything more than background radiation. That means that:
1) They didn't set off a nuclear device;
2) They did, and it was extremely well sealed and far underground (possible); or
3) They kind of did, but it fizzled and was in a well sealed cavern far under ground (likely).
Drudge sites no source, and just has a single line so take that for what you will.
cdg