(Reuters) – Ukraine stepped up calls for financial sanctions crippling enough to force Moscow to end the war and its officials rushed to evacuate civilians from cities and towns in the east before an anticipated major Russian offensive there. FIGHTING * Capturing Mariupol is still the main focus of Russian troops and Russian battalions are blockading and bombarding the northeastern city of Kharkiv, the Ukrainian military said. * Kremlin spokesman Dmitry Peskov said Russia had sustained “significant losses” in Ukraine. * The United States will send new weapon systems to Ukraine, after NATO fore…