Putin oversees nuclear drills as U.S. warns Russia ready to invade Ukraine

The latest:

Russian President Vladimir Putin launched exercises by strategic nuclear missile forces on Saturday, and Washington said Russian troops amassed near Ukraine's border were "poised to strike."

As Western nations fear the start of one of the worst conflicts since the Cold War, U.S. Defence Secretary Lloyd Austin said Russian forces were beginning to "uncoil and move closer" to the border with its former Soviet neighbour.

"Having done this before, I can tell you that that's exactly what you need to attack and the stance that you need to be in to attack," Austin said at a news conference on a visit to Lithuania.

Lithuanian Foreign Affairs Minister Gabrielius Landsbergis said he was concerned that if the Kremlin was willing to take Ukraine, Moscow would next target the Baltic states and Poland. Austin vowed Washington would stand with its Baltic allies but declined to be drawn in on whether he would answer Lithuanian calls for additional troops.

Russia ordered the military buildup while demanding NATO stop Ukraine from ever joining the alliance but says predictions it is planning to invade Ukraine are wrong and dangerous. It says it is now pulling back while Washington and allies insist the buildup is mounting.

Russian-backed separatist leaders in Eastern Ukraine earlier declared a full military mobilization, a day after ordering women and children to evacuate to Russia, citing the threat of an imminent attack by Ukrainian forces.

Kyiv flatly denied the accusation, and both it and Washington say increased shelling across the ceasefire line this week is part of Russia's plan to create a pretext for an invasion of Ukraine.

Ukraine's military said shelling killed a soldier on Saturday in the government-held part of the Donetsk region and that separatist forces were placing artillery in residential areas to try to provoke a response.

Multiple explosions could be heard on Saturday morning near Donetsk in Eastern Ukraine as more people got on buses to leave, a Reuters witness said. The origin was not immediately clear. Ukraine said earlier that one of its soldiers had been killed.

The Kremlin said Putin, who pledged to protect Russia's national interests against what it sees as encroaching threats from the West, was watching the nuclear drills together with Belarusian President Alexander Lukashenko from the situation room in the Kremlin.

Notably, the planned exercise involves the Crimea-based Black Sea Fleet. Russia annexed the Crimean Peninsula after seizing it from Ukraine in 2014. .

Underscoring the West's concerns of an imminent invasion, a U.S. defence official said an estimated 40 per cent to 50 per cent of the ground forces deployed in the vicinity of the Ukrainian border have moved into attack positions closer to the border.

U.S. President Joe Biden, who has given regular warnings of an impending invasion, said on Friday he now believes the capital Kyiv would be targeted by Russia but that he does not think Putin is even remotely contemplating using nuclear weapons.