In the next few years, having secured mainland Iran, the new Iranian king set out to reconquer the Caucasus and to re-impose its traditional suzerainty over the region. After Heraclius II refused to denounce the treaty with Russia and to voluntarily reaccept Iran's suzerainty in return for peace and prosperity for his kingdom, Agha Mohammad Khan invaded Kartli-Kakheti, captured and sacked Tbilisi, effectively bringing it back under Iranian control. This was short-lived, however, for Agha Mohammad Khan was assassinated two years later. Heraclius II himself died a year after that.