The United States believes Russia now has “probably” as many as 190,000 troops, including Russian-backed separatists forces, according to a U.S. envoy, in and around Ukraine amid fears that Russian capabilities of a full-fledged invasion continue to grow.

“We assess that Russia probably has massed between 169,000 to 190,000 personnel in and near Ukraine as compared with about 100,000 on January 30,” Michael Carpenter, U.S. ambassador to the Organization for Security and Cooperation in Europe (OSCE), said in a statement Friday. “This estimate includes military troops along the border, in Belarus, and in occupied Crimea; Russian National Guard and other internal security units deployed to these areas; and Russian-led forces in eastern Ukraine.”

Unlike this latest assessment, previous estimations by U.S. officials did not include separatist forces in eastern Ukraine.

“While Russia has sought to downplay or deceive the world about their ground and air preparations, the Russian military has publicized its large-scale naval exercises in the Black Sea, Baltic Sea and the Arctic,” Carpenter said. “Russia has publicly said the Black Sea exercise alone involves more than 30 ships, and we assess that amphibious landing ships from the Northern and Baltic Fleets were sent to the Black Sea to augment forces there.”

The OSCE is a Cold War-era European security forum that has deployed a war monitor in eastern Ukraine for years and hosted talks on the current crisis with Russia. Its foundational documents have been used selectively by Moscow to paint Ukraine and NATO as a threat to Russia’s security, even as its envoy in Vienna has largely dismissed dialogue there.

Earlier this week, Ukraine requested an emergency OSCE meeting to demand Russia explain its massive military buildup after Moscow ignored Kyiv’s inquiry. Russia skipped Wednesday’s session just as it did Friday’s, where Carpenter delivered these remarks.

Meanwhile, Ukrainian Defense Minister Oleksii Reznikov told his country’s parliament Friday that they assess Russia has about 149,000 troops near their borders.

-ABC News Conor Finnegan and Cindy Smith