Predawn explosions hit the one bridge linking the occupied Crimean Peninsula to mainland Russia on Monday, damaging a significant image of President Vladimir V. Putin’s claims to sovereignty over Ukrainian territory and briefly disrupting a serious provide line to Russian troops.

The blasts had been the second time the Kerch Strait Bridge has been hit in 10 months. And although these inflicted far much less harm than an explosives-laden truck that blew up last October, they uncovered the vulnerability of the bridge — and different Russian provide routes removed from the entrance — as Ukraine wages a grueling counteroffensive to retake land.

Russia on Monday accused Ukraine of utilizing maritime drones to assault the bridge, a strategic hyperlink for Russian forces combating in southern Ukraine. Ukrainian officers celebrated the assault, however neither claimed nor denied duty for the blasts.

Hours after the assault, Moscow introduced that it was pulling out of the Black Sea grain deal, an settlement that had allowed Ukraine to export its grain by sea regardless of Moscow’s naval blockade. Dmitri S. Peskov, the Kremlin’s spokesman, mentioned the bridge assault was not associated to Russia’s resolution to droop its participation within the deal, which had helped hold world meals costs steady.

Rail service over the bridge resumed Monday morning. But harm to the automobile lanes, which appeared to have left a part of the highway tilting, in accordance with video verified by The New York Times, threatened to constrict Russian logistical operations.

If the bridge had been destroyed or severely broken, Moscow could be left with a single main land route from Russia, alongside the southern coast of Ukraine, to assist tens of hundreds of troopers combating to carry onto territory captured within the first weeks of its invasion.

Mr. Putin, in a gathering with transportation officers broadcast on state TV, condemned the explosions as “another terrorist attack perpetrated by the Kyiv regime.” He mentioned the Ministry of Defense was getting ready Russia’s response and that Russia’s most important safety service, the F.S.B., would examine.

“Given that this is the second terrorist attack on the Crimean bridge,” Mr. Putin mentioned, “I am waiting for concrete proposals to improve the security of this strategically important transportation facility.”

One bridge section was destroyed, and one other was dislocated by greater than 30 inches, in accordance with Marat Khusnullin, a Russian deputy prime minister. But the principle assist pillars remained intact, which Mr. Putin referred to as “good news.”

Mr. Khusnullin mentioned restricted car visitors may resume as quickly as Tuesday. Less broken lanes could be restored by mid-September, and the remainder of the lanes by November, he mentioned.

Pro-war Russian navy bloggers and commentators described the assault, which officers mentioned killed two folks and injured a 3rd, as proof of one other failure by the Russian navy command. Igor Girkin, a former Russian intelligence officer who runs a outstanding weblog, mentioned that Ukraine would strike time and again till the bridge hyperlink is severed.

The assault got here as Ukrainian forces had been engaged in a grinding counteroffensive, now five-weeks previous, geared toward driving Russian forces from areas of southern and jap Ukraine. Russian forces are dug in behind fields laden with land mines, so the Ukrainian navy has been compelled to maneuver cautiously and progress has been slow.

Isolating Russian forces in Crimea is an important a part of the Ukrainian counteroffensive technique, in accordance with analysts. Ukrainian floor forces have been in search of to drive a wedge by way of the pure land bridge that connects Russia to the peninsula by way of southern Ukraine, and have repeatedly focused the bridge, which Mr. Putin ordered constructed after Russia illegally annexed Crimea in 2014.

When the bridge opened in 2018, Mr. Putin hailed it as a “remarkable” achievement that strengthened Crimea. With its opening, he mentioned, “all of us are even closer to each other.”

The explosion that hit the bridge final October was large enough to rupture fuel tanks on a passing train, setting it on fireplace, and pulled a part of the roadway off its joints and into the ocean. Ukrainian officers didn’t acknowledge any function till months later, however have referred to as the 12-mile bridge a reliable navy goal due to its very important logistical function within the Kremlin’s battle effort.

“Any illegal structures used to deliver Russian instruments of mass murder are necessarily short-lived, regardless of the reasons for the destruction,” Mykhailo Podolyak, a senior adviser to President Volodymyr Zelensky of Ukraine, said on Twitter on Monday.

After the October assault, Moscow stepped up countermeasures to defend the construction, deploying a ship with an array of radar reflectors to guard the bridge.

A Russian company, the National Anti-Terrorism Committee, mentioned in an announcement that Ukraine attacked the bridge on Monday with two maritime drones, a declare that might not be independently verified. Video and images verified by The Times confirmed essentially the most important harm alongside a span of the bridge heading into Russia. One photograph additionally confirmed a broken automobile on the bridge.

Though taking down a bridge in wartime has traditionally been troublesome, airborne and waterborne drones could present new methods to focus on the weakest factors.

“Precision-guided weapons, where you can hit a specific part of the bridge, make it less difficult to knock it out,” mentioned Samuel J. Cox, a retired rear admiral and the director of the Naval History and Heritage Command in Washington. “That allows you to get to a specific point on the bridge where you can do more damage.”

But bridge designs have improved through the years, which means a bridge typically retains the structural integrity to be repaired, as a substitute of getting to get replaced.

“I would think the Russians would be able to fix this fairly quickly,” Admiral Cox mentioned.

Milana Mazaeva, Ivan Nechepurenko, James Glanz and Axel Boada contributed reporting.