Russia's Defense Ministry declared a unilateral ceasefire in Ukraine for Friday and Saturday to mark the 81st anniversary of the defeat of Nazi Germany in World War II, but it threatened to strike back at Kyiv if it tries to disrupt the Victory Day festivities.Russian servicemen await the rehearsal of the Victory Day military parade, to be held at Red Square, in central Moscow (AFP)The Defense Ministry said in a statement Monday that it hoped Ukraine "will follow suit" on the ceasefire for Russia's most important secular holiday. There was no immediate comment from Ukrainian authorities.Authorities last week decided to…