By Natalia Zinets and Max Hunder KYIV (Reuters) -Russian forces captured territory along a frontline river in eastern Ukraine and intensified pressure on two key cities on Monday, after Ukrainian President Volodymyr Zelenskiy predicted Moscow would escalate attacks ahead of an EU summit expected to welcome Kyiv’s bid to join the bloc. The governor of Ukraine’s Luhansk region, scene of the heaviest Russian onslaughts in recent weeks, said the situation was “extremely difficult” along the entire frontline there as of Monday evening. “The Russian army has accumulated sufficient amount of reserves…