Ukraine to invade? Russia plotting? Rumors fly in Moldova amid protests.

Rolling street demonstrations are threatening to destabilize another fragile post-Soviet state. But in this case, it’s not pro-Western protesters pushing back against what they see as an authoritarian drift by their government, but pro-Russian demonstrators complaining about deteriorating living standards – and, also, creeping authoritarianism.

Crowds are surging through the streets of Chisinau, the capital city of tiny Moldova, the poorest country in Europe. But fallout from the war in next-door Ukraine has made economic prospects even worse and aggravated social tensions.

What makes Moldova’s situation especially dangerous is the presence next to...