FILE - Sergei Ivanov, Russia's special representative for environment protection and transport, attends a Victory Day military parade marking the 75th anniversary of the Nazi defeat in World War II on Moscow's Red Square, Russia, Wednesday, June 24, 2020. (AP Photo/Pavel Golovkin, Pool, File)
FILE- Russian President Vladimir Putin, right, listens to his chief of staff Sergei Ivanov during a meeting in the Kremlin in Moscow, on Monday, March 24, 2014.(Alexei Nikolsky, Sputnik, Kremlin Pool Photo via AP)
FILE - Russian Premier Dmitry Medvedev, left, Deputy Premier Sergei Ivanov, center, and Russian President Vladimir Putin walk after a state-of-the nation address in Moscow, Russia, Wednesday, Dec. 12, 2012. (AP Photo/Misha Japaridze, File)
FILE - Russian President Vladimir Putin, right, and Kremlin's Chief of Staff Sergei Ivanov attend a meeting of the V-Day celebrations organizing committee in the Kremlin in Moscow, Russia, Tuesday, March 17, 2015. (AP Photo/Sergei Ilnitsky, Pool, File)
FILE - Russian Defense Minister Sergei Ivanov greets U.S. Secretary of State Condoleezza Rice during their meeting in Moscow, Thursday, June 29, 2006. (AP Photo, File)
FILE - Sergei Ivanov, Russia's special representative for environment protection and transport, attends a Victory Day military parade marking the 75th anniversary of the Nazi defeat in World War II on Moscow's Red Square, Russia, Wednesday, June 24, 2020. (AP Photo/Pavel Golovkin, Pool, File)
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FILE- Russian President Vladimir Putin, right, listens to his chief of staff Sergei Ivanov during a meeting in the Kremlin in Moscow, on Monday, March 24, 2014.(Alexei Nikolsky, Sputnik, Kremlin Pool Photo via AP)
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FILE - Russian Premier Dmitry Medvedev, left, Deputy Premier Sergei Ivanov, center, and Russian President Vladimir Putin walk after a state-of-the nation address in Moscow, Russia, Wednesday, Dec. 12, 2012. (AP Photo/Misha Japaridze, File)
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FILE - Russian President Vladimir Putin, right, and Kremlin's Chief of Staff Sergei Ivanov attend a meeting of the V-Day celebrations organizing committee in the Kremlin in Moscow, Russia, Tuesday, March 17, 2015. (AP Photo/Sergei Ilnitsky, Pool, File)
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FILE - Russian Defense Minister Sergei Ivanov greets U.S. Secretary of State Condoleezza Rice during their meeting in Moscow, Thursday, June 29, 2006. (AP Photo, File)
MOSCOW (AP) — Sergei Ivanov, a former Russian defense minister once seen as a possible successor to President Vladimir Putin, has died. He was 73.
The Kremlin said Ivanov died on Friday without providing the cause of death or giving other details. Putin sent his condolences to Ivanov's family.
Putin and Ivanov knew each other since the 1970s when they both worked as young KGB officers in their hometown of Leningrad, as St. Petersburg was called during the Soviet times.
When Putin was first elected in 2000, Ivanov served as secretary of Russia's Security Council. In 2001, Putin made Ivanov his defense minister, the job he held until 2007, overseeing the second war in that crushed the region’s separatist bid.
When Putin decided to step down due to term limits and shift into the prime minister's seat in 2008, Ivanov was widely viewed as his most likely successor. However, Putin picked another longtime associate, , to serve as his placeholder until reclaiming the presidency in 2012. Some observers argued that Putin ditched Ivanov's candidacy because he saw Ivanov as overly ambitious and feared that he could try to hold onto the presidential seat.
Ivanov remained at Putin's side as deputy prime minister from 2007-2011, and then served as the Kremlin chief of staff from 2011-2016.
In 2016, Ivanov was named a presidential envoy for environment protection and transport, a job that carried no political weight and was widely seen as a honorary retirement. He stepped down earlier this year.
Along with other Russian top officials, Ivanov has been targeted by the U.S. and the EU sanctions in response to Moscow's military action in Ukraine.