KYIV—President Volodymyr Zelenskiy called on NATO on Tuesday to lay out a path for Ukraine to join the Western military alliance, after days in which Russia has massed troops near the conflict-hit Donbass region. Zelenskiy’s comments drew an immediate rebuke from Moscow, which said Kyiv’s approach to NATO could further inflame the situation in Donbass, where violence has increased in recent days. Russian-backed separatists have fought since 2014 against Ukrainian forces in the Donbass, a conflict that Kyiv says has killed 14,000 people. Kyiv reported two more soldiers killed on Tuesday. “NATO is the only way to end the war in Donbass,” Zelenskiy told NATO Secretary General Jens Stoltenberg in a phone call, according to a statement from Zelenskiy’s office. A Membership Action Plan laying out Ukraine’s entry path into the alliance “will be a real signal for Russia,” he said. He also called for NATO members to strengthen their …