The BUFFs are between Prague and Leipzig now, I presume they were sending a message to Vlad.
LL - someone may be monitoring you. - they temporarily vanished from ADS-B around the time you posted.
I have been watching the Romanian Border Guard Schiebel Camcopter S-100 which has been very active off the coast for the last couple of days, not so much obvious ISTAR activity today though a Global Hawk has been active all day, didn't see an E-3 until late/mid afternoon, I assume some of the missions are more covert than others and have stronger EMSEC. Various models of RC-135 including both RAF and USAF RJs, E-3s and a JSTARS yesterday.
The E-3 crew who flew a BBC team had clearly been well briefed on what not to say.