Interesting variation on NATO's ISTAR fleet which we've seen swanning around Russia and Ukraine during the present "unpleasantness".
This morning's Jake21 is a WC-135R Constant Phoenix (64-14836), out of Mildenhall, just dropped down to 5500 ft over the Baltic around Kaliningrad. Rather than Electronic Reconnaissance, its normal mission is to collect atmospheric samples to monitor radiation fallout. Wonder what it's sniffing?