Kyiv, Ukraine CNN  — 

Tensions between Ukraine and Russia are at their highest in years, with a Russian troop build-up near the two nations’ borders spurring fears that Moscow could launch an invasion.

Ukraine has warned that Russia is trying to destabilize the country ahead of any planned military invasion. Western powers have repeatedly warned Russia against further aggressive moves against Ukraine.

The Kremlin denies it is planning to attack and argues that NATO support for Ukraine – including increased weapons supplies and military training – constitutes a growing threat on Russia’s western flank.

The picture is complicated – but here’s a breakdown of what we know.

What’s the situation on the border?

The United States and NATO have described the movements and concentrations of troops in and around Ukraine as “unusual.”

As many as 100,000 Russian troops have remained amassed at the Ukrainian border, despite warnings from US President Joe Biden and European leaders of serious consequences should Putin move ahead with an invasion. And US intelligence findings in December estimated that Russia could begin a military offensive in Ukraine “as soon as early 2022.”

Speaking alongside his Ukrainian counterpart in Kyiv on January 19, US Secretary of State Antony Blinken said Russia had “ratcheted up its threats and amassed nearly 100,000 forces on Ukraine’s border, which it could double on relatively short order.”

In late 2021, satellite photos revealed Russian hardware – including self-propelled guns, battle tanks and infantry fighting vehicles – on the move at a training ground roughly 186 miles (300 km) from the border.

The Ukrainian Defense Ministry’s latest intelligence assessment says Russia has now deployed more than 127,000 troops near Ukraine, including some 21,000 air and sea personnel, transferred more Iskander operational-tactical missiles to the bord