The Jan. 17 end of sanctions on Iran will have important consequences worldwide, changing the state of play in the ongoing conflicts in Syria and Yemen . In the South Caucasus, however, Tehran's reemergence will have particularly sweeping effects. For some time, Iran has lagged far behind its regional rivals in terms of economic and military influence, even as it has become increasingly interested in Azerbaijan, Georgia and Armenia for their transit and energy possibilities. Iran has a number of reasons for increasing its regional involvement. Europe is trying to diversify away from Russian natural gas , and Iran wants to seize the opportunity to take over these markets. But it needs access to the South Caucasus first. Tehran recently expressed interest in using existing infrastructure such as the Trans-Anatolian Gas Pipeline and the Trans-Adriatic Pipeline, which connect the Caspian and Mediterranean seas.