The United States is seeing some Russian personnel withdrawing after a huge buildup near Ukraine but it is still early and Moscow’s announcement of its redeployment alone is “insufficient to give us comfort,” a senior U.S. defense official told Reuters on Friday.

“It’s a bit too soon to tell exactly what forces are withdrawing and exactly what equipment appears to be left behind. But I can just tell you, we’re looking very, very closely,” the official said, speaking on condition of anonymity.

Russia announced on Thursday it had completed a “snap inspection” of military drills in its south and west after weeks of tensions with the West over its concentration of tens of thousands of troops near Ukraine that had raised concerns in Kyiv and the West about the risk of war.

The remarks appeared to be the first U.S. confirmation of any pullback in forces. Ukraine had given a guarded welcome to Russia’s announcement of the troop drawdown.

“If Russia really pulls back from the border with Ukraine, the enormous military force it has deployed there, this will already ease tensions,” Ukrainian Foreign Minister Dmytro Kuleba said in a statement.

But the drills seemed anything but ordinary to observers in Kyiv and the West. The White House said Russia had more troops on Ukraine’s eastern border than at any time since 2014, when it annexed Crimea and backed separatist seizures of territory in eastern Ukraine.

The Ukrainian president’s spokeswoman estimated earlier in April that Russia had more than 40,000 troops deployed on Ukraine’s eastern border and over 40,000 in Crimea. Around 50,000 of those forces were new deployments, she said.

“We knew that it was unusual. We knew that Russia’s statement that this is just a normal training exercise … (was) inconsistent with what we would have expected to see,” the U.S. official said.

“We were joined by a chorus of allies that were also equally concerned because they, too, couldn’t really reconcile what they were seeing with something that would be an ordinary training mission.”

Moscow said it had ordered troops involved in exercises to return to their bases by May 1.

Military hardware was to be left at a training ground near Voronezh, a Russian city about six hours’ drive from Ukraine, so that it could be used again in another big scheduled exercise later this year.

The senior U.S. defense official criticized Moscow for failing to notify or explain its drills under international agreements.

The troop buildup near Ukraine was one of several issues that have raised tensions between Russia and the West.

Reuters