The fiery blast on the Kerch Bridge on Saturday triggered a chorus of calls for brutal retaliation against Ukraine among Russian public figures who support President Vladimir Putin.

The calls increase political pressure on Putin, who said in September that Moscow is ready to use “all available means” to protect the country and its people “if our country is threatened.”

“This is not a bluff,” Putin added, speaking during the announcement of the mobilization of 300,000 reservists for the war on Ukraine.

His statement triggered speculation among Ukraine’s Western backers about a possible deployment of tactical nuclear weapons against Ukrainian troops in case Kyiv is successful in its counteroffensive in four Ukrainian territories formally annexed by the Kremlin, or if Ukraine attempts to win Crimea back. Kyiv hasn’t claimed responsibility for the bridge explosion.

Sergei Markov, a Kremlin-connected politician and former parliamentarian with Putin’s United Russia party, believes that “the terrorist attack” on the Kerch Bridge is evidence that “the U.S. and its Ukrainian proxy regime will move the red line further and further.”

“No response from Russia? Even further. And again? Even further,” he wrote on social media, demanding a tough response from Moscow.

Konstantin Dolgov, a member of the upper house of Russia’s parliament, also branded the explosion “a terrorist attack” and “another sinister manifestation of the terrorist nature of the puppet Kyiv regime.”

Referring to Ukrainian President Volodymyr Zelenskyy, Dolgov said: “Terrorists must be treated unequivocally!”

Rodion Miroshnik, who represented in Moscow until recently the Russia-backed Luhansk People’s Republic, wrote on social media that “undamaged Ukrainian bridges across the Dnieper river look ridiculous against the backdrop of a blazing Crimean bridge.”

The damage to the Kerch Bridge, which connects Russia with Crimea, the peninsula illegally annexed by Moscow in 2014, not only poses a problem to Russia’s supplies of manpower and weapons to its units in southern Ukraine. It is also a serious humiliation for Putin personally, having happened on the morning after his 70th birthday.

The explosion was also a slap in the face to propagandists in Russia’s state-controlled media, who have regularly used the bridge as a symbol of Russia’s successful annexation of Ukrainian territory.

Television journalist Vladimir Solovyov, sanctioned earlier this year by the EU for his propaganda activities, wrote in his Telegram channel: “It’s time to respond. By all means available.”

He said that Ukraine “must be immersed in dark times,” and urged Russia to destroy bridges, dams, railways, thermal power plants and other infrastructure facilities in Ukraine. According to international law, such deliberate destruction would be a war crime. The U.N. already said last month that Russia had committed war crimes in Ukraine including the bombings of civil areas and summary executions.

Andrei Medvedev, a prominent television journalist and a vice speaker of the Moscow city council, said that “what will happen to us [Russia] depends, among other things, on the reaction [of the authorities] to today’s events.”