Them, when they get the air sample, they can then determine what radioactive material, what isotopes are really in the year. but, and this is a big "but," what we're learning is, today the prevailing winds in that area are headed north. that might carry any air samples north, into china, into russia. there would be international sensor networks there that could report some of the activity. but it might not let the u.s. get exactly what it would like to get. still, they are looking at seismic activity. and the conclusion is this was the biggest test that the north koreans have conducted so far....