The Russian build-up on the Ukraine border is unmistakable, according to experts. The satellite images from the area show Russia amassing battle tanks and other heavy military machinery. Russian President Vladimir Putin, while denying the “evidence” blamed NATO instead of increasing activity in Ukraine, which posed a threat to Russia. (https://foreignpolicy.com/2021/11/01/us-russia-military-movement-ukraine/)

The Russia-Ukraine border has been tense ever since the protests in Ukraine deposed a pro-Russian Ukrainian president in 2014, and Russia backed rebels and then involved itself later, leading to heavy casualties in eastern Ukraine.

While claiming that Russia was plotting a coup in the country, Ukraine has accused Russia of amassing over 90,000 troops near its border.

Recently, U.S. Secretary of State, Antony Blinken had also expressed concerns at Russia’s moves, saying that Russia could rehash what it did in 2014. It could be looking for a reason to provoke and attack Ukraine. (https://www.state.gov/secretary-antony-j-blinken-and-ukrainian-foreign-minister-dmytro-kuleba/)

Ukraine's President Volodymyr Zelensky cited intelligence recordings to bolster claims that Russian "representatives" were planning to overthrow his government as early as next week with the help of people sympathetic to Russia within his country, including wealthy business people. "There is a threat today that there will be war tomorrow. We are entirely prepared for an escalation,” Zelensky said. (https://www.bbc.com/news/world-europe-59288181)

Meanwhile, Nato's Secretary-General Jens Stoltenberg has warned that Russian use of force against Ukraine would "come at a cost.”

In the 2014 war, Russia annexed a large part of Crimea, which was part of Ukraine until then. Ukraine says that Russia could attack its Donbas region. Russia has dismissed the fears saying that it was not interested. (https://www.youtube.com/watch?v=EMpMTda8lHo)

Read more:

Why Ukraine fears a coup next week:
https://www.washingtonpost.com/world/europe/ukraine-zelensky-russia-coup/2021/11/26/16e51c80-4e0d-11ec-a7b8-9ed28bf23929_story.html