Vladimir Putin is expected to deliver a national speech later – his first since ordering his troops to Ukraine in February.
There had been speculation in Russian news media that he would speak with Russians on Tuesday evening, but this did not happen and no reason was given.
It comes after separatist leaders in four Russian-occupied regions of eastern Ukraine announced plans to hold referendums on joining Russia later this week.
Putin is expected to defend the move, which would pave the way for the formal annexation of parts of the territory after nearly seven months of war.
The self-proclaimed Donetsk (DPR) and People’s Republics of Luhansk (LPR), which Mr Putin recognized as independent states just before the February 24 invasion, have both said they will hold referendums from this Friday and until Tuesday.
The regions of Kherson and Zaporizhzhya, which have yet to be recognized as independent states by Russiahave also said they will keep their own votes.
Ukrainian President Volodymyr Zelenskyy said the situation clearly shows his country took the initiative in the conflict, adding that “noisy news from Russia” would not change Ukraine’s position.
The White House said the US will reject plans to hold referendums, while Ukraine dismissed the move as a stunt by Moscow to try to reclaim the initiative after crushing losses on the battlefield.
And French President Emmanuel Macron said the referendums will not be recognized by the international community.
NATO chief Jens Stoltenberg tweeted: “Sham referendums have no legitimacy and do not change the nature of Russia’s war of aggression against Ukraine. This is a further escalation in Putin’s war. The international community must condemn this flagrant violation of international law and step up support for Ukraine.”
Moscow does not fully control any of the four regions, with only about 60% of the Donetsk region in Russian hands, but if it goes through with the referenda and joins Russia in all four, Ukraine – and possibly its Western backers – from a Russian perspective, fighting against Russia itself.
‘Panic’ in Kremlin amid Ukraine’s counter-offensive – all latest Ukraine news, live
That would increase the risk of a direct military confrontation between Russia and NATO’s military alliance, a scenario that US President Joe Biden says could lead to World War III as NATO members supply weapons and intelligence to Ukraine.
Commentators agree the move could escalate Moscow’s confrontation with the West if it comes after recent territorial gains by Ukrainian troops pushed Russian troops very much into the background.
The world has been waiting as Mr Putin ponders his next steps after the crushing pushbacks.
Analysis: Russia takes new stance after being thrown back by swift Ukrainian offensive
Ukraine said the threat of referendums was “naive blackmail” and a sign that Russia was getting scared.
“This is what the fear of defeat looks like. The enemy is afraid and veils primitively,” said Chief of Staff Andriy Yermak of Mr. Zelenskyy.
Dmitry Medvedev, a former Russian president who is currently Vice-President of the Security Council, suggested that the outcome of any referendums would be irreversible.
The territory Russia currently controls in Ukraine covers more than 90,000 square km, or about 15% of the country’s total area – equivalent to the size of Hungary or Portugal.
Russia annexed Crimea in 2014. With Crimea and territory in the other four regions, Russia would cover an area of approximately 120,000 square kilometers, roughly the same size as the US state of Pennsylvania. England is about 130,000 square kilometers in size.