The forensic tent, covering the bench where Sergei Skripal and his daughter Yulia were found, is repositioned by officials in protective suits in the centre of Salisbury, Britain, March 8, 2018.

Law enforcement officers detain a participant of a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, Russia July 27, 2019.

Pro-Russian armed men take cover behind a car near the local police headquarters in Luhansk, eastern Ukraine, April 29, 2014.

Russian special forces remove hostages from a besieged theatre where Chechen guerrillas were holding hundreds captive in Moscow October 26, 2002.

During an economic crisis, President Yeltsin names little-known security chief Vladimir Putin as his fifth acting prime minister in less than a year, and says he wants Putin to succeed him as president. In the following weeks, bombings of apartment blocks across Russia kill more than 300 people, in attacks Putin blames on Chechen militants. His popularity is boosted by his tough response, which includes the aerial bombing of parts of Chechnya and an assault to recapture the breakaway southern province. Some Kremlin critics question if Chechen militants were really behind the apartment bombings. REUTERS/Pool

December 2019 - Putin boasts of his country's lead in hypersonic weapons and says other countries are trying to catch up. (Pictured: Putin visits the National Defence Control Centre to oversee the test of a new Russian hypersonic missile system called Avangard.) Sputnik/Mikhail Klimentyev/Kremlin via REUTERS

Russia's President Vladimir Putin makes a point during his speech at the Bayerischer Hof hotel during the 43rd Conference on Security Policy in Munich, February 10, 2007.

A couple stands next to armed servicemen outside a Ukrainian border guard post in the Crimean town of Balaclava March 1, 2014.

Governors of Russian regions attend a session of the State Council, headed by President of Russia Vladimir Putin in the Kremlin on June 1, 2004.

The Kursk nuclear-powered submarine sinks to the bottom of the Barents Sea, killing all 118 crew after an explosion onboard. Putin's image suffers a jolt after he comments on the crisis only after four days. REUTERS/Stringer

A Russian police officer carries a released baby from the school seized by heavily armed masked men and women in the town of Beslan. A Russian police officer carries a released baby from the school seized by heavily armed masked men and women in the town of Beslan in the province of North Ossetia near Chechnya, September 2, 2004. An armed gang, holding hundreds of people hostage in a Russian school, on Thursday freed four infants and at least two women.

A Russian sailor leaves a polling booth with his ballot papers at a polling station in St.Petersburg, March 14, 2004.

Russian President Vladimir Putin listens during annual news conference in Moscow, Russia December 20, 2018.

Dec. 31, 1999 - An ailing Yeltsin resigns and names Putin acting president. REUTERS/Itar Tass

Jailed Russian former oil tycoon Mikhail Khodorkovsky (C) and his business partner Platon Lebedev (R) stand behind a glass wall during a court session in Moscow November 2, 2010.

Investigative journalist Anna Politkovskaya (pictured), a critic of rights abuses in Chechnya, is murdered in Moscow on Putin's birthday. Kremlin critic Alexander Litvinenko dies in London that same year after being poisoned with a radioactive substance. A British inquiry years later concludes he was killed by Russian agents. REUTERS/

Putin wins his first presidential election. REUTERS/Gleb Garanich

Russia's President Dmitry Medvedev (R) and former president Vladimir Putin (L) stand after the inauguration ceremony at the Kremlin in Moscow, May 7, 2008.

Soviet President Mikhail Gorbachev signs his resignation minutes before a live address on national television on December 25, 1991.

Civil defense members extinguish a military vehicle at a base controlled by rebel fighters from the Ahrar al-Sham Movement, that was targeted by what activists said were Russian airstrikes in the south of Idlib province, Syria October 1, 2015.

Activists scuffle during an opposition protest on Revolution square in central Moscow February 26, 2012.

A Russian soldier walks past destroyed Georgian tanks in the South Ossetian capital of Tshinvali, August 10, 2008.

Russian President Vladimir Putin (C) and Russian Olympic medal winning athletes pose for a picture in Sochi February 24, 2014.

FIFA president Gianni Infantino, President of Russia Vladimir Putin and President of France Emmanuel Macron stand during the presentation during the World Cup at the Luzhniki Stadium in Moscow, Russia, July 15, 2018. REUTERS/Kai Pfaffenbach

Putin wins a landslide re-election victory and a mandate to stay in office until 2024. Yuri Kadobnov/POOL via Reuters