 Rhadamistus then executed Mithridates and his sons, despite a promise of non-violence, and became King of Armenia.Of this usurpation, Tacitus wrote "Rhadamistus might retain his ill-gotten gains, as long as he was hated and infamous; for this was more to Rome's interest than for him to have succeeded with glory".However, faced with this upset of the regional balance and fearing that Armenia and Iberia would unite as a single powerful kingdom in the hands of Rhadamistus, Tiridates entered Armenia with Parthian support in 53 AD.