According to unnamed US officials, Russia has stationed more than 100,000 troops near its border with Ukraine amid escalating tensions, but Moscow has denied planning to attack, and claimed its troops are in the region for military drills.

Without providing evidence for their assessment, the US officials said the information was based on intelligence but that they were unable to give details due to its sensitivity, while the officials also said they did not know if Russian President Vladimir Putin had decided to take such a step.

"A diplomatic solution is still possible," two US officials said on condition of anonymity.

The officials said weather conditions would provide a peak window for the Russian military to move its heavy equipment forward between about Feb 15 and the end of March.

File image of Ukrainian military convoy from Wikimedia Creative Commons

Fearing that the Russian invasion of Ukraine could lead to more than 50,000 civilian casualties, the officials estimated that a full-scale attack could see the Ukrainian capital, Kyiv, fall within days and prompt a refugee crisis in Europe as millions of people will flee.

Meanwhile, being concerned that the Kremlin is planning to launch an assault on Ukraine, additional US troops have been arriving in Poland as part of a new deployment to bolster the Western military alliance NATO's forces in the region, reported BBC.

According to the British national broadcaster, following the Biden administration's announcement of deploying 3,000 additional US troops to Eastern Europe, the first group landed at Rzeszow in the south-east of the country on Saturday.

File photo by US Army via Wikimedia Creative Commons

However, downplaying the possible incursion by Russia as estimated by the US sources, Ukraine Foreign Minister Dmytro Kuleba on Sunday said they do not to believe the “apocalyptic predictions”, adding that "Ukraine is ready for any development with its strong army, unprecedented international support, and Ukrainians’ faith in their country.

"The enemy should be afraid of us, not us of them," Kuleba tweeted.

A week ago, accusing Washington and the media of fuelling panic that weighed on the economy when there were "no tanks in the streets", the Ukrainian President Volodymyr Zelenskyy said the country was not a sinking Titanic.

The border tensions come nearly eight years after Russia annexed Ukraine's southern Crimea peninsula and backed a bloody rebellion in the eastern Donbas region, while Moscow has accused the Ukrainian government of failing to implement the Minsk agreement, which sought to end war in the Donbas region of Ukraine.

Ukrainians learn to handle weapons for self-defences

According to media reports, Ukrainians are training to handle arms and defend themselves under the shadow of a possible Russian invasion.

A New York Post report said tens of thousands of ordinary people in Ukraine are learning to handle weapons, render first aid and perform other combat-related skills.

"Citizens are turning to experts in firearms, and even just family members, in hopes of surviving an attack and facing down their belligerent neighbor," the report said.

“My daughter, now 23, taught me how to shoot,” Vlad Horbovetz, a surgeon and volunteer medic, told The Post.

According to the New York Times,  thousands of Ukrainian civilians have signed up to learn combat skills in training programmes  run by the government and private paramilitary groups.