Russian President Vladimir Putin says Ukraine's statehood could suffer an "irreparable blow" if the pattern of the war continues, and Russia would never be forced to abandon the gains it has made.
Putin made his televised comments a day after Switzerland agreed to host a global summit at the request of Ukrainian President Volodymyr Zelenskiy.
Putin dismissed "so-called peace formulas" being discussed in Europe and Ukraine and what he called the "prohibitive demands" they entailed.
"Well, if they don't want (to negotiate), then don't!" he said.
"Now it is quite obvious, not only (Ukraine's) counter-offensive failed but the initiative is completely in the hands of the Russian armed forces. If this continues, Ukrainian statehood may suffer an irreparable, very serious blow."
Putin's statements about the course of the war have become increasingly confident and aggressive in recent months, with the failure of Ukraine's counter-offensive to deliver any substantial gains against well entrenched Russian forces.
Russia controls 17.5 per cent of the territory of Ukraine.
Putin said talk of negotiation was "an attempt to motivate us to abandon the gains that we have realised over the past year and a half. But this is impossible. Everyone understands that this is impossible".
A peace formula put forward by Zelenskiy calls for the restoration of Ukraine's territorial integrity, cessation of hostilities and withdrawal of Russian troops.
Russia says any negotiation would have to take account of the "new realities" created by its forces on the ground.
Zelenskiy urged the international community on Tuesday to tighten sanctions pressure on Putin and to step up its support for Ukraine to ensure that Russia did not succeed in its war.
Hesitation in backing Ukraine and fears of an escalation in the war with Russia were costing time and lives, and could prolong the fighting by years, he told the World Economic Forum in Davos in an emotional speech.
Zelenskiy said that Europeans needed to understand that Putin's plans went beyond the war in Ukraine.
"In fact, Putin embodies war... He will not change... We must change. We all must change to the extent that the madness that resides in this man's head or any other aggressor's head will not prevail," Zelenskiy said.
Nearly two years after Russia launched its full-scale invasion, Zelenskiy said he strongly opposed freezing the conflict along its current lines.
"Putin is a predator who is not satisfied with frozen products," he said.
He said sanctions on Russia needed to be enforced properly and that the lack of sanctions on the country's nuclear sector were an illustration of the international community's weakness.
"Of course, I am grateful for each package of sanctions... Thank you. But bringing peace closer will be a reward for all those who care to ensure that sanctions work one hundred per cent," he said.
NATO Secretary-General Jens Stoltenberg, also speaking at Davos, said support for Ukraine was not charity but an investment in the alliance's own security.
"We just have to stand by Ukraine. At some stage, Russia will understand that they are paying too high a price and sit down and agree to some kind of just peace - but we need to stand by Ukraine," he stated.
Zelenskiy met senior officials earlier on the sidelines of the forum, including US Secretary of State Antony Blinken, US National Security Advisor Jake Sullivan, NATO's Stoltenberg and international investors such as executives from JPMorgan.
