President Joe Biden spoke with Russian President Vladimir Putin by phone on Tuesday and proposed the two estranged leaders meet at a summit in a third country to discuss a raft of disputes, the White House said. The Kremlin said Wednesday it was premature to talk in tangible terms about a possible summit, saying it would consider Biden’s proposal. The call between the two presidents—officially only the second since Biden took office—took place as Western powers have grown increasingly alarmed at Russian troop buildup near the Ukrainian border, with fears that a rash move by Moscow or Kyiv could spark an outbreak of fresh hostilities. Tensions have grown in recent weeks in Donbass, eastern Ukraine, where government forces have battled Russian-backed separatists in a simmering seven-year conflict that Kyiv says has killed 14,000 people. In their phone call, Biden asked Putin to take steps to lower the temperature around the …