Why Lyman matters for Russia's odds in the Ukraine War

Ukrainian forces are pushing ahead with their counteroffensive after recapturing a key eastern town from Russia. The Ukrainian military says it struck several Russian command posts and ammunition depots. Moscow's defense military is also claiming to have destroyed Ukrainian missile depots.
President Zelenskyy says Lyman in the eastern Donetsk region has been quote "fully cleared" of Russian troops, who retreated from the town on Saturday.
US defense minister Lloyd Austin said Ukraine's victory in Lyman would be a strategic headache for Russia as it seeks to hold off the counteroffensive elsewhere.