audie? the context for this of course, is the counteroffensive that ukraine has been running the last couple weeks. so are we looking at retaliation or a possibility this is part of that effort? reporter: it s hard to say. the ukrainians have been involved without a source unknowing whether they were behind today s incident in moscow. but they have done a variety of things. they are aimed to sort of undermine public confidence in the ability of moscow to actually run the country. so, for instance, there have been cross border incursions into russia. there have been regular drone attacks on across the border in areas in southern russia. therefore this is really more than anything part of a psychological warfare effort against the russians. it goes back quite some time. so it s hard to say whether this is part of the counteroffensive, but it s definitely an attempt to just shake the confidence of