Ukraine, Stalled on the Front, Steps Up Sabotage, Targeting Trains

The saboteurs managed to place four explosives on a Russian freight train carrying diesel and jet fuel, roughly 3,000 miles from the Ukrainian border. But more important than the destruction of the train, Ukrainian intelligence officials said, was the timing of the blast.

They needed it to blow up as the 50 rail cars were traveling through the nine-mile-long tunnel through the Severomuysky mountains, the longest train tunnel in Russia.

The Ukrainians were hoping to compromise a vital conduit for weapons being shipped to Russia from North Korea, at a moment when Ukrainian forces on the front are struggling to stave off relentless Russian assaults. Trains can be replaced and tracks quickly repaired. But serious damage to this tunnel, which took decades to build, might not be so easy to fix.

Russia and Ukraine continue to battle on a large scale, both on the ground and with aerial strikes. Russian officials accused Ukraine of attacking a Russian city, Belgorod, on Saturday, killing at least 20 people and injuring more than 100 others, in apparent response to a huge Russian missile barrage on several Ukrainian cities the day before.

But guerrilla tactics — including sabotage, commando raids, targeted assassinations and attempts to blow up ammunition depots, oil pipelines and railways — have taken on added importance as the two sides fail to make substantial advances at the front.

So at 5:20 p.m. on Nov. 29, a fire ripped through the tunnel, Russian Railways reported. Russian media broadcast footage of flames around the tunnel entrance, and officials said the explosion was caused by “the detonation of an unidentified explosive device.”