Russia wants to kill US diplomats (why? All of them? Some of them? One of them?) so rather than doing some botched robbery or fake suicide... they invent a "direct energy weapon" to kill them?
Or maybe they're researching this cool new direct energy weapon and they decide to test it out on... US diplomats? You'd think they could pick a less conspicuous target to test out their assassination laser beams.
Definitely withholding judgement until we learn more.