Within hours of a blast that damaged the sole bridge linking Crimea with Russia early Saturday, hard-line military bloggers and Russian officials were calling for a swift and strong response from Moscow.

One high-level politician said that anything less than an “extremely harsh” response would show weakness from the Kremlin, which is facing continued losses on the battlefield and mounting criticism at home.

For President Vladimir V. Putin of Russia, who presided over the bridge’s opening in 2018, the explosion seemed to be a highly personal affront, underscoring his failure to get a handle on a relentless series of Ukrainian attacks.

Some news media commentators demanded that Russia destroy Ukraine’s electricity infrastructure and the transportation systems used to import Western armaments.

Evgeny Poddubny, a war correspondent for the state RT outlet, said that nobody in the Ukrainian leadership seemed to fear Russia anymore.

“The enemy has stopped being afraid, and this circumstance needs to be corrected promptly,” he wrote in RT’s Telegram channel. “Commanders of formations, heads of intelligence agencies, politicians of the Kyiv criminal regime sleep peacefully, wake up without a headache and in a good mood, without a sense of inevitability of punishment for crimes committed.”

Aleksandr Kots, a war correspondent for the Russian tabloid Komsomolskaya Pravda, wrote on Telegram that disabling the bridge bodes ill for Moscow’s already troubled efforts to hold onto territory in the Kherson region of southern Ukraine — and most likely foreshadowed a future attack on Crimea itself.

He described the “consistency” that Ukraine was showing in the war as “enviable” and called for Russia to “hammer Ukraine into the 18th century, without meaningless reflection on how this will affect the civilian population.”

While there were no official claims of responsibility, Ukrainian officials, who in the past have said the bridge would be a legitimate target for a strike, indicated that the explosion was no accident and made no secret of their satisfaction.

“Crimea, the bridge, the beginning,” Mykhailo Podolyak, an adviser to Ukraine’s president, wrote in a Twitter post on Saturday. “Everything illegal, must be destroyed. Everything stolen returned to Ukraine. All Russian occupiers expelled.”

The explosion is emblematic of a Russian military in disarray. Russian forces were unable to protect the road and rail crossing despite its centrality to the war effort, its personal importance to Mr. Putin and its potent symbolism as the literal connection between Russia and Crimea.

For Russia, the rail crossing “has played a key role in moving heavy military vehicles to the southern front during the invasion,” the British defense intelligence agency wrote in its daily assessment on Sunday. It added that although the extent of the damage to the rail line was uncertain, “any serious disruption to its capacity will highly likely have a significant impact on Russia’s already strained ability to sustain its forces in southern Ukraine.”

Hours after the explosion, the Kremlin appointed Gen. Sergei Surovikin, yet another new commander, to oversee its forces in Ukraine. Previous leadership shake-ups have done little to right the military’s floundering performance.

General Surovikin, 55, has long had a reputation for corruption and brutality, military analysts said.

“He is known as a pretty ruthless commander who is short with subordinates and is known for his temper,” said Michael Kofman, the director of Russia studies at C.N.A., a defense research institute based in Virginia.

His appointment was quickly praised by some of the biggest supporters of the war, including Yevgeny Prigozhin, the founder of the Wagner mercenary group that was deployed heavily in Syria. He made a rare public endorsement of the general, calling him “legendary.”