Moscow's military buildup includes air and sea components and its ally Belarus "should be considered as a full-fledged theater of operations," says Kiev's new intelligence assessment, according to CNN.
Russia has reportedly deployed more than 127,000 troops and "almost completed" its buildup, Ukraine has said, raising fears of an imminent invasion of the eastern European country.
"The full strength of RF AF (Russian Federation's Armed Forces) land group at the Ukrainian direction — (is) over 106,000 personnel. Together with the sea and air component, the total number of personnel is over 127,000 servicemen," US broadcaster CNN reported citing Ukraine Defence Ministry's latest intelligence assessment.
The assessment said the current situation in the region is "difficult" and added that it believes Moscow is "trying to split and weaken the European Union and NATO."
Ukraine's assessment also said that Russia was using its ally Belarus to "expand aggression" against Kiev.
"The territory of Belarus should be considered as a full-fledged theater of operations that Russia can use to expand aggression against Ukraine," the intelligence document added.
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Russia could attack 'at any point'
On Tuesday, the US also upped its threat assessment, saying Russia is ready to attack Ukraine at "any point."
"We're now at a stage where Russia could at any point launch an attack on Ukraine," Press Secretary Jen Psaki told reporters.
"I would say that's starker than we have been."
Psaki's characterisation of the situation around Ukraine came as Secretary of State Antony Blinken was scheduled to meet Russian Foreign Minister Sergey Lavrov on Friday in Geneva.
Meanwhile, a senior US State Department official said Russian troops being deployed in Belarus for what Moscow and Minsk say will be joint military exercises are raising concerns that they "potentially" could be used to attack neighbouring Ukraine.
The US is also worried that draft constitutional reforms in Belarus could lead to the deployment of Russian nuclear weapons in the country, a senior State Department official told reporters.