Explosion on only bridge linking the Crimean Peninsula to Russia

News Desk: A fireball consumed two sections of the only bridge linking the occupied Crimean Peninsula to Russia on Saturday, disrupting the most important supply line for Russian troops fighting in southern Ukraine and dealing an embarrassing blow to the Kremlin, which is facing continued losses on the battlefield and mounting criticism at home.

The blast and fire sent part of the 12-mile Kerch Strait bridge tumbling into the sea and killed at least three people, according to Russian authorities, who said a Ukrainian truck bomb had caused the blast. That claim could not be independently verified and the Ukrainian government, which lauded the damage, stopped short of taking responsibility for the attack.

For President Vladimir V. Putin of Russia, who presided over the bridge’s opening in 2018, the explosion, was a highly personal affront, underscoring his difficulties in the face of continued Ukrainian successes.

The full extent of the damage was not immediately clear. The bridge has spans for train and automobile traffic, and Russia’s transportation department said the railroad section of the bridge could be repaired by Saturday evening. Even so, Russian officials and hard-line military bloggers were already calling for revenge, with one member of Crimea’s Parliament warning that anything less than an “extremely harsh” response would show weakness.

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

Any serious impediment to traffic on the bridge could have a profound effect on Russia’s ability to wage war in southern Ukraine, where Ukrainian forces have been fighting an increasingly effective counteroffensive. The bridge is the primary military supply route linking Russia with the Crimean Peninsula. Without it, analysts said, the Russian military will be severely limited in its ability to bring fuel, equipment and ammunition to Russian units fighting in the Kherson and Zaporizhzhia regions, two of the four Ukrainian provinces that Mr. Putin announced Russia had annexed on Sept. 30.

Russia’s National Anti-Terrorism Committee said in a statement that a truck had exploded on the automobile side of the bridge, igniting seven fuel cisterns being pulled by a train on a parallel crossing headed in the direction of Crimea. The explosion caused two sections of the bridge to partly collapse.

While there were no immediate claims of responsibility, Russian and Ukrainian officials indicated that the explosion was no accident, and top Ukrainian officials, who in the past have said the bridge would be a legitimate target for a Ukrainian strike, 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.”

Ukraine’s domestic intelligence agency, the Security Service of Ukraine, known by its Ukrainian acronym S.B.U., issued a statement rephrasing a stanza of a poem by Ukraine’s national poet, Taras Shevchenko. “Dawn, the bridge is burning beautifully,” the agency posted on Twitter. “A nightingale in Crimea meets the S.B.U.”