The protests that started after Ukrainian President Viktor Yanukovych’s decision to withdraw its association with the European Union have led to growing unrest in parts of Ukraine, souring the relationship between Russia and the West.

Here are some of events that highlight the key moments in the crisis.

Nov. 21, 2013: Protesters take to the streets after Yanukovych’s government announces plans to abandon an agreement that would strengthen ties with the European Union and instead seeks closer cooperation with Moscow.

Nov. 30, 2013: Police attack a group of protesters in Kiev. Images of protesters bloodied by the police spread quickly throughout the country, helping to generate more public support for the demonstrations.

Dec. 17, 2013: Russian President Vladimir Putin announces that Moscow will buy $15 billion worth of Ukrainian government bonds and allow for a sharp cut in the price Ukrainians pay for Russian natural gas.

Jan. 22, 2014: Two protesters die after being hit with live ammunition and a third one dies during a confrontation between police and demonstrators at barricades.

A coffin with the body of a protester killed in clashes is carried through the crowd in Independence Square in Kiev. (Efrem Lukatsky/AP)

Jan. 28: The prime minister resigns and parliament repeals the new strict anti-protest laws that had set off violence a week earlier.

Feb. 16: Opposition activists end their occupation of Kiev’s city hall in exchange for the release of all 234 jailed protesters in what is seen as a sign of progress toward resolving the crisis peacefully.

Feb. 18: Clashes leave at least 26 people, including 10 police officers, dead and hundreds injured. The violence begins when protesters attack police lines and set fires outside parliament after it stalls on taking up a constitutional change to limit presidential powers.

Feb. 20: Clashes erupt between protesters and police, leading to numerous casualties, just hours after a truce had been announced.

Feb. 21: Yanukovych signs an agreement with opposition leaders to hold early elections, dilute his powers and form a caretaker government. But many of the protesters demand his removal.

Feb. 22: Parliament votes to dismiss Yanukovych and frees his rival, jailed opposition leader Yulia Tymoshenko, who addresses tens of thousands of people in Independence Square.

Ukraine's former prime minister Yulia Tymoshenko, seen here in 2011, is freed from prison. (Sergei Svetlitsky/AFP/Getty Images)

Feb. 23: Pro-Russia protesters start rallying in Crimea, where Russia has a major naval base.

Feb. 26: Leaders of Ukraine’s protest movement propose legislator Arseniy Yatsenyuk as prime minister.

Feb. 27: Masked gunmen seize regional parliament and government buildings in Crimea. Yanukovych is granted refuge in Russia.

Feb. 28: Ukraine says Russian troops have taken up positions around strategic locations on the Crimean Peninsula.

March 1: Troops under apparent Russian command take over Crimea without firing a shot. President Obama calls Putin to demand the troops’ withdrawal. Ukraine says there are up to 16,000 Russian troops in Crimea. Russia says it has approved troop deployment at the request of Yanukovych.

March 6: Crimea’s parliament declares the region wants to join Russia and will let voters decide in a March 16 referendum.

Communist Party members and supporters hold their red flags near a Lenin monument in Simferopol. (Max Vetrov/AFP/Getty Images)

March 14: A last-ditch diplomatic effort before the referendum fails in London, where Secretary of State John Kerry meets with Russian Foreign Minister Sergei Lavrov amid threats of sanctions against Russia if it annexes Crimea.

March 16: Official results from Crimea’s secession referendum say 97 percent of voters back a proposal to join Russia.

March 24: Ukrainian troops leave Crimea, following emotional farewells to spouses and family members left behind.

April 7: Protesters occupy government buildings in the eastern cities of Donetsk, Luhansk and Kharkiv, calling for a referendum on independence. Ukraine authorities regain control of Kharkiv government buildings the next day.

April 11: Ukraine’s Interim Prime Minister Arseniy Yatsenyuk offers to devolve more powers to the eastern regions, as pro-Russia occupations in Donetsk and Luhansk continue.

April 18: The United States, Russia, Ukraine and the European Union reach an agreement for armed groups to disarm and end occupations of public buildings and spaces.

April 24: Ukraine sends in its troops again to drive away separatist rebels in Slavyansk. The following day, rebels detain eight international observers from the OSCE,accusing them of being spies. The observers were released a week later.

May 7, 2014: Putin calls for pro-Russian separatists in the eastern part of the country to postpone a planned Sunday referendum that could exacerbate violence. He also said the Russian military has pulled back from the Ukrainian border, where troops had massed in recent weeks.

May 12, 2014: After claiming victory in the controversial self-rule vote, armed insurgents in eastern Ukraine promptly demanded that Ukrainian security forces leave the separatists’ “sovereign” territory and urged Russia to consider absorbing it.

Sources: Washington Post, Associated Press, Reuters