SLOVYANSK, Ukraine -- When shadowy Cmdr. Igor Strelkov appeared before the cameras recently in green combat fatigues and a clipped mustache, he did more than reveal the face of the insurgency rocking eastern Ukraine. He strengthened the case that Russia is behind the turmoil.
The commander did not address Ukraine and European Union assertions that he is a Russian intelligence officer. But he told journalists that he and his men entered Ukraine from Crimea, which Russia annexed in March after an insurgency that Russian President Vladimir Putin now admits involved Russian troops. Cmdr. Strelkov's assertion that many of the insurgents are not locals undermines rebel claims that the insurgency is a spontaneous uprising, rather than a coordinated operation backed by outside forces.
"The militia is, of course, strongly sprinkled with volunteers from other regions," Cmdr. Strelkov said in a taped interview with Russian tabloid Komsomolskaya Pravda. He estimated that a third of the fighters are not Ukrainian. He backtracked Tuesday in an interview with Russian TV, claiming that 90 percent of the militiamen were Ukrainian.
The EU on Tuesday included Cmdr. Strelkov among 15 new people targeted by sanctions. EU documents identify him as a member of the Russian military intelligence agency GRU, as do Ukrainian authorities. He himself was cryptic about his origins in the weekend interview.
Equally murky are the origins of Cmdr. Strelkov's insurgents, their operations and weapons. They have proven themselves to be ruthless and effective, running their campaign with unerring foreknowledge of Ukrainian security operations. He said his forces obtained their weapons partly from police buildings they had taken over as well as from Ukrainian forces they fought when they entered eastern Ukraine last month. "Russia so far hasn't supplied us with a single machine gun or bullet," he said.
The insurgents are seeking more autonomy from Kiev -- possibly even independence or annexation by Russia. Ukraine's acting government and the West have accused Moscow of orchestrating the unrest, which they fear could be used as a pretext for a Russian invasion.
The belief that the Kremlin is directing the insurgents -- whose mysterious origins and green fatigues have won them the moniker "little green men" -- gained credence when Mr. Putin last month dropped his denials that the Russian army had been deployed in Crimea during the uprising there.
But there are differences between that situation and eastern Ukraine. The pro-Russian fighters here are substantially less numerous than in Crimea. And they fall into two broad categories: men in uniform with skills of professional soldiers and less-organized local militiamen.
The former, dressed in balaclavas and a variety of military-style fatigues without insignia, have been deployed in rapid government office seizures. On Monday, a gang of about 15 such men with Kalashnikovs seized a building housing the city hall and city council in Kostyantynivka, 100 miles west of the Russian border. At least one had a rocket-propelled grenade launcher.
A clearly less-professional crew patrols checkpoints in and around Slovyansk, the insurgent headquarters. Typically dressed in civilian clothing, these local men are mostly armed with simpler weapons. Some carry hunting guns, others just sticks.
A clear tie to Russia is hard to pin down. Mr. Putin denies his forces are in eastern Ukraine, and his foreign ministry calls such claims "flimsy insinuations."
The eerie skill with which the green men anticipate Ukraine's every security move offers strong circumstantial evidence of Russian involvement. On April 13, Ukrainian special forces poised to launch a strike on Slovyansk were pre-emptively attacked by a handful of suspected pro-Russian troops. Last weekend, three Ukrainian special services agents were kidnapped and presented to Russian journalists with signs of beatings.
Both Western and Ukrainian experts say the events suggest Ukrainian security services have been infiltrated by Russian intelligence.