In a late-night press conference, the Russian leader also said his troops would not stop pushing forward in Ukraine and sought to undermine his Ukrainian counterpart Volodymyr Zelensky.

The Western military alliance will hold a crucial summit in The Hague next week to discuss increasing defence spending to five percent of GDP, under pressure from US President Donald Trump.

Putin has cast his offensive in Ukraine as part of a wider conflict between Russia and US-led NATO, which has been Ukraine's staunchest backer since Russia launched its offensive in February 2022.

"We do not consider any rearmament by NATO to be a threat to the Russian Federation, because we are self-sufficient in terms of ensuring our own security," Putin said at a televised press conference in Saint Petersburg.

Russia is "constantly modernising our armed forces and defensive capabilities," Putin said, adding that it made "no sense" for NATO to spend more money on arms.

Though he conceded higher spending by NATO would create some "specific" challenges for Russia, he brushed them off.

"We will counter all threats that arise. There is no doubt about that," Putin added.

Kyiv is seeking security guarantees from NATO as part of any deal to end the fighting, more than three years after Russia ordered its full-scale military offensive.

- Zelensky meeting? -

Moscow has shown little willingness to back down, with Putin saying Thursday that Russia had the "strategic advantage" on the battlefield.

"Our troops are advancing along the entire line of contact. Every day, more or less, but every day they go forward. And the advance will continue," he said.

Putin also sought to justify his three-year campaign against Ukraine, questioned Zelensky's legitimacy and dismissed civilian deaths from Russia's daily aerial attacks.

He said he was ready to meet with his Ukrainian counterpart, but only during a "final phase" of negotiations on ending the three-year conflict.

He also suggested Zelensky had no right to sign a peace agreement given his five-year mandate had expired, a notion Kyiv has dismissed as baseless propaganda.

"We need to find a solution that would not only put an end to the current conflict, but also create conditions that would prevent similar situations from recurring in the long term," Putin said.

"I am ready to meet with everyone, including Zelensky. That is not the issue -- if the Ukrainian state trusts someone in particular to conduct negotiations, for God's sake, it can be Zelensky," the Russian leader said.

"We don't care who negotiates, even if it is the current head of the regime," Putin said.

But he added that this would only happen at a "final phase, so as not to sit there and divide things up endlessly, but to put an end to it."

Putin has rejected Zelensky's calls for a face-to-face meeting to agree a peace deal.

Moscow has also rejected proposals for a full and unconditional ceasefire, and outlined a raft of hardline peace demands -- including that Kyiv cede more territory and renounce Western military support.

Kyiv has dismissed them as "ultimatums" and accused Moscow of deliberately sabotaging peace efforts to prolong the conflict.

Russia has escalated its aerial attacks on Ukraine amid the stalled talks.

Russian strikes on the Ukrainian capital killed at least 28 people on Wednesday, Kyiv said.

Despite widespread evidence of massive civilian deaths amid the campaign and the destruction of apartments, schools, hospitals and other sites, Putin on Thursday claimed that his forces did not target civilian areas.

Hours earlier, AFP journalists in Kyiv had watched rescuers carry body bags with victims out of a destroyed apartment block across piles of debris.