I'm still going with own-goal. ELINT or countermeasures. Why? Because the constant in this is US embassies not where it's detected. Some Canadians, they're in five-eyes.<p>The people most likely to have pulsed energy sources are the people who actively explore them. The US actively esplores pulsed energy for offence, for defence and for open ended science. There's sufficient hatred between all players that it's highly unlikely only the US and a few Canadians would be the targets and yet insufficient UK, Australian, NZ or EU sources have stood up and said "me too" even after persisting problems with the FSU and China.<p>I see no reason to suspect any external threat higher than an own goal.