President Vladimir Putin warned the West on Wednesday not to cross Russia's "red lines", saying Moscow would respond swiftly and harshly to any provocations in a way that would force those behind them to regret their actions.
Putin made his comments at a time when relations with the United States and Europe are under acute strain over Ukraine and the health of jailed opposition leader Alexei Navalny.
"We want good relations...and really don't want to burn bridges," Putin said in his annual state of the nation address to both houses of parliament.
"But if someone mistakes our good intentions for indifference or weakness and intends to burn down or even blow up these bridges, they should know that Russia's response will be asymmetrical, swift and harsh."
Russia would determine where its red line lay in each specific case, he said.
His comments came at the climax of a 78-minute speech dominated by Russia's response to the Covid-19 pandemic and resulting economic hardship.
Recent weeks have seen an intensification of confrontation between Russia and Western countries which say Moscow is massing tens of thousands of troops near Ukraine.
Last week, Washington tightened sanctions on Russia over accusations of computer hacking and election interference, and the Czech Republic accused Moscow of a role in explosions at an arms depot in 2014. Both expelled Russian diplomats. Russia denied wrongdoing and responded with tit-for-tat expulsions.
Putin made no mention of Navalny, the jailed opposition politician three weeks into a hunger strike, whose supporters, even as Putin spoke, were beginning a series of rolling protests across the country.
Two of Navalny's closest allies were arrested on Wednesday, their lawyers said. Lyubov Sobol, one of the faces of Navalny's popular YouTube channel, and Kira Yarmysh, his spokeswoman, were both detained in Moscow.
"As usual, they think that if they isolate the 'leaders', there won't be any protest," said Leonid Volkov, a close Navalny associate. "Of course that's wrong."
Another Navalny aide, Ruslan Shaveddinov, tweeted: "Right now across the whole of Russia they are detaining potential protesters. This is repression. This cannot be accepted. We need to fight this darkness."
Navalny, Russia's leading opposition politician, is gravely ill in prison following his decision to launch a hunger strike in protest against what he calls inadequate medical treatment for leg and back pain. His team have urged people across the vast country to take to the streets on Wednesday.
The government has said the planned gatherings are illegal. Previous pro-Navalny rallies have been dispersed by force, with thousands of arrests.