NICE, France (AP) — Russia’s military has launched a string of attacks on Ukraine’s railway network, which has been vital for moving Western arms to Ukrainian forces, evacuating refugees and exporting food.

A Russian official said the aim was to disrupt Western weapons deliveries. Experts say Ukraine’s railways appeared to be largely spared at the start of the invasion because Russian planners wanted them to move their own troops and arms across captured territory. The latest strikes still seem to seek more to damage than to destroy the system.

Here’s a look at the attacks, and their significance.

WHY ARE RAILWAYS SO IMPORTANT FOR UKRAINE?

The largely flat country has a vast railway network, which has proved invaluable from a military viewpoint for supplying key Western arms shipments — and has also helped in the exodus of refugees from Russian air assaults and land advances.

Western weaponry pouring into Ukraine helped its forces blunt Russia’s initial offensive. It also seems certain to play a central role in the battle for the Donbas in the east, which Moscow now says is its focus following its failure to take the capital, Kyiv.

The U.S. and other Western allies have increased weapons shipments at the urging of Ukrainian President Volodymyr Zelenskyy. Russian Defense Minister Sergei Shoigu warned that Moscow will see any Western transport carrying weapons into Ukraine as a legitimate target.

The rail attacks were meant to disrupt the delivery of Western weapons, Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said Wednesday.

WHAT WERE THE LATEST TARGETS?

Russian forces used sea- and air-launched precision guided missiles to destroy power facilities at five railway stations across Ukraine over the past day.

Some attacks were concentrated in and around the western city of Lviv, close to the border with Poland that has been a gateway for the NATO-supplied weapons. Lviv’s mayor said the strikes damaged three power substations, knocking out electricity in parts of the city that has seen only sporadic attacks during the war and has become a haven for civilians fleeing the fighting.

HAS THE RAILWAY SYSTEM BEEN STRUCK BEFORE?

A Russian missile hit a crowded train station in eastern Ukraine last month, killing at least 52 people and wounding dozens more.

Thousands of civilians, mostly women and children fleeing the Donbas region, had gathered at the station in the town of Kramatorsk on April 8 when a missile hit.

Zelenskyy accused Russia’s military of deliberately attacking the station. Russia blamed Ukraine, saying its own forces don’t use the kind of missile that hit the station.

In late April, Russian targeted several railway junctions in the west of the country to disrupt weapons deliveries.

WHAT IS RUSSIA’S PLAN?

Russia seems to have largely spared Ukraine’s rail system at the outset of the invasion because it had planned to use it to move its own troops and arms across the country, which it had hoped to overrun quickly, military experts say.

“Now that they know they won’t be able to use it, they are striking the rail system that is likely carrying armor and reinforcements to the Ukrainians,” said retired French General Dominique Trinquand.

While Russians have been conducting precision attacks on the rail network and firing expensive missiles into its power supply lines in the past week, their goal still appears to be damaging rather than destroying the network.

“It won’t stop the Ukrainians, but it will disrupt them,” said Frank Ledwidge, a former British military intelligence officer. He said the Russians also aim to undermine Ukraine’s morale.

“It’s like saying, ‘Nowhere is safe’, ‘Your army can’t protect you’, ‘We reign over your country at will.'”

WHAT DOES THE US SAY?

A senior U.S. defense official, speaking on condition of anonymity to discuss the Pentagon’s assessment, said that while the Russians have tried to hit critical infrastructure around Lviv, specifically targeting railroads, there has been “no appreciable impact” on Ukraine’s effort to resupply its forces.

The official said it is not clear that the Russian strikes have been very accurate, and they also have not impeded efforts to get weapons into Ukraine.

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Jon Gambrell in Lviv, Cara Anna in Zaporizhzhia, Ukraine, Lolita C. Baldor in Washington and John Leicester in Le Pecq, France contributed to this report.

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