Russian military exercises in Belarus will continue, Minsk announced Sunday, leaving Moscow with a large force near the northern Ukraine border as Western powers warn of an imminent invasion.
The announcement came as French President Emmanuel Macron called Russia's Vladimir Putin for talks the Elysee described as "the last possible and necessary efforts to avoid a major conflict in Ukraine."
Moscow had previously said the 30,000 troops it has in Belarus were simply carrying out readiness drills with its ally, which would be finished by Feb. 20, allowing the Russians to head back to their bases.
But, as the day arrived for the operation to end, the Belarus defence ministry said Putin and Belarusian leader Alexander Lukashenko had decided to "continue inspections," citing increased military activity on their shared borders and an alleged "escalation" in Eastern Ukraine.
The move will be seen as a further tightening of the screws on Ukraine, already facing increased shelling from Russian-backed separatist rebels and a force of what Western capitals says is more than 150,000 Russian personnel on its borders.
It will also be seen as a rebuff to efforts by leaders like Macron and Germany's Chancellor Olaf Scholz to urge their Russian counterpart to pull back from the brink of war.
More bombardments were heard by AFP reporters overnight close to the frontline between government forces and the Moscow-backed rebels who hold parts of the districts of Lugansk and Donetsk.
"Every indication indicates that Russia is planning a full-fledged attack against Ukraine," NATO chief Jens Stoltenberg said, echoing U.S. President Joe Biden, who believes the invasion is imminent.
The Moscow-backed separatists have accused Ukraine of planning an offensive into their enclave, despite the huge Russian military build-up on the frontier.
Kyiv and Western capitals ridicule this idea, and accuse Moscow of attempting to provoke Ukraine and of plotting to fabricate incidents to provide a pretext for a Russian intervention.
"Russian military personnel and special services are planning to commit acts of terror in temporarily-occupied Donetsk and Lugansk, killing civilians," alleged Ukraine's top general Valeriy Zaluzhniy.
"Our enemy wants to use this as an excuse to blame Ukraine and move in regular soldiers of the Russian armed forces, under the guise of 'peacekeepers'," the military chief of staff said.
The rebel regions have made similar claims about Ukraine's forces and have ordered a general mobilisation, while staging an evacuation of civilians into neighbouring Russian territory.
Officials with the Lugansk rebels claimed Sunday they had repulsed an attack by Ukrainian forces that had left two civilians dead, but the Ukrainian interior ministry immediately denounced the claim as an "absolute fake."
Russian investigators said they had opened a probe into the alleged incident.
Russia, according to Western leaders, has more than 150,000 troops along with missile batteries and warships massed around Ukraine, poised to strike.
Ukrainian President Volodymyr Zelenskiy told Macron on Saturday he would not respond to Russia's provocations, according to the Elysee.
But in his speech to the Munich Security Conference, he also condemned "a policy of appeasement" towards Moscow.
"For eight years, Ukraine has been holding back one of the greatest armies in the world," he said.
He called for "clear, feasible timeframes" for Ukraine to join the U.S.-led NATO military alliance — something Moscow has said it would never accept, as it tries to roll back Western influence.
Western officials in Munich warned of enormous sanctions if Russia attacks, with U.S. Vice President Kamala Harris saying this would only see NATO reinforce its "eastern flank."
On Saturday, from the Kremlin situation room, Putin and Lukashenko watched the launch of Russia's latest hypersonic, cruise and nuclear-capable ballistic missiles.
Putin has also stepped up his rhetoric, reiterating demands for written guarantees that NATO roll back deployments in eastern Europe to positions from decades ago.
"The big question remains: does the Kremlin want dialogue?" European Council President Charles Michel asked at the Munich Security Conference. "We cannot forever offer an olive branch while Russia conducts missile tests and continues to amass troops."
The volatile front line between Ukraine's army and Russian-backed separatists has seen a "dramatic increase" in ceasefire violations, monitors from the OSCE European security body have said.
Hundreds of artillery and mortar attacks were reported in recent days, in a conflict that has rumbled on for eight years and claimed more than 14,000 lives.
The OSCE said there had been 1,500 ceasefire violations in Donetsk and Lugansk on Friday alone, and AFP reporters in the area have heard heavy shelling since.
On Saturday, a dozen mortar shells fell within a few hundred metres (yards) of Ukraine's Interior Minister Denys Monastyrskiy as he inspected a frontline position with journalists in tow.