Sergei Ivanov, Russia's ex-defense minister once seen as Putin's likely successor, has died at 73

Former defense minister Sergei Ivanov, a longtime Putin ally and ex-KGB colleague, has died at 73; the Kremlin gave no cause of death.
Once seen as a possible successor to Putin, Ivanov was later passed over in favor of Dmitry Medvedev and remained a close aide in various roles.
In later years he held largely ceremonial posts (stepping down earlier this year) and was among Russian officials sanctioned by the U.S. and EU over Ukraine.