President Putin has traveled to Iran for the third time in a decade. The Russian president attended a trilateral summit with Iran and ex-Soviet state Azerbaijan in Tehran. Putin met with Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei and President Hassan Rouhani. Moscow and Tehran have had close military and economic relations for some time. Russia has already built a nuclear reactor at Iran's Bushehr power plant and started work on the second one.