(Reuters) – Russian forces were launching an all-out assault to encircle Ukrainian troops in twin cities straddling a river in eastern Ukraine on Tuesday, a battle which could prove decisive for Moscow’s main campaign in the east. DIPLOMACY * Kyiv must win the war against Moscow, making the invasion of Ukraine a strategic failure for Russia’s President Vladimir Putin, European Commission President Ursula von der Leyen told global business leaders in Davos. * Russia has not yet seen an Italian peace plan for Ukraine, but hopes to receive it through diplomatic channels, Kremlin’s spokesperson sa…