The 1994 Budapest Memorandum on Security Assurances affirmed Russia's commitment to respect the territorial integrity of Ukraine, including Crimea, and refrain from the threat or use of force against Ukraine's territorial integrity or political independence.

The 1997 Russian-Ukrainian Treaty on Friendship, Cooperation, and Partnership reaffirmed the inviolability of borders between Russia and Ukraine, required Russian forces in Crimea to respect Ukraine's sovereignty, honor its legislation, and not interfere in its internal affairs.

In 2001, a federal constitutional law was adopted in Russia regarding the admission of new federal subjects. It stated that admission of a foreign state or its part into Russia must be based on mutual agreement between the two countries.

In November 2013, tens of thousands of Ukrainians protested in Kyiv after the pro-Moscow president Viktor Yanukovych refused to sign an association deal with the EU.

In January 20, 2014, the first signs of the creeping annexation of Crimea by Russia emerged with trucks without license plates and Russian soldiers, known as 'little green men', appearing on the peninsula. Russian Cossacks were also formed under the guise of local self-defense units, leading to escalating instability in Crimea.

The government brutally cracked down on the continued protests in Kyiv, resulting in the deaths of around 108 civilians, many by police snipers, with the peak of violence occurring on 18 to 20 February.

Members of the Sevastopol City Council petitioned President Viktor Yanukovych to take strict measures against the opposition leaders, holding them responsible for inciting armed confrontation. This action reflected the growing tensions and divisions within Crimea during the Ukrainian revolution.

On February 20, 2014, the armed aggression in Crimea started with illegal crossing of the Ukrainian state border near the Kerch Strait by the Russian Armed Forces. This event marked the beginning of the occupation of Crimea by Russia.

Following Yanukovych's departure, anti-Ukrainian protests in Crimea intensified on February 21, 2014. Ukrainian government offices in Crimea and Sevastopol began to resist orders from Kyiv.

Tens of thousands protested in Sevastopol and Simferopol, establishing parallel administrations and civil self-defense squads. Protesters refused to pay taxes to the state, waved Russian flags, and chanted pro-Putin slogans. Russian military convoys were also reported in the area.

After an all-night meeting with security services chiefs, Russian President Vladimir Putin expressed the need to start working on returning Crimea to Russia, due to concerns about the new Ukrainian government's alignment with the West.

Pro-Russian demonstrators, including neo-Cossacks, rallied outside Sevastopol administration offices demanding a Russian citizen as mayor. They planted Russian flags at city hall and distributed leaflets calling for volunteers to a militia, sparking further unrest.

On February 25, several hundred pro-Russian protesters gathered outside the Crimean parliament, demanding a referendum on Crimea's status and non-recognition of the central government of Ukraine. Tensions rose as rumors spread about possible arrests by security forces.

Russian troops, following orders from President Vladimir Putin, seized control of the main route to Sevastopol in Crimea. A military checkpoint with Russian military presence was established on the highway between Sevastopol and Simferopol.

On February 27, unmarked Russian forces, along with nationalist paramilitaries, seized control of the Autonomous Republic of Crimea and Sevastopol. Russian flags were raised over government buildings, and barricades were erected. This marked the beginning of the Russian takeover of Crimea.

A group of armed men in military uniform without identification seized control over Simferopol International Airport and local TV tower, believed to be Russian Black Sea Fleet troops.

From March 1 to 16, Russian military and paramilitary formations captured the main military facilities and administrative buildings of Crimea. The number of Russian military personnel increased to 20 thousand servicemen.

By March 2, 2014, Russian troops, including those without insignia, had complete control over the Crimean Peninsula. They operated from Sevastopol and mainland Russia, effectively blockading the Southern Naval Base.

Ukrainian troops stationed in Crimea were given an ultimatum by Alexander Vitko, the commander of the Russian Black Sea Fleet, to surrender by March 3 at 5 a.m. or face armed confrontation. The ultimatum was later denied by Russian officials.

On March 4, 2014, the Ukrainian General Staff reported the presence of Russian military units in Crimea, violating international agreements. Despite this, Putin publicly denied plans to annex Crimea or invade Ukraine.

The Crimean government announced that soldiers and officers from several Ukrainian regiments stationed in Crimea defected to the Crimean side, showing support for defending the population of Crimea.

The Supreme Council of Crimea voted to formally re-accede as part of the Russian Federation after 60 years of being part of Ukraine. A referendum was scheduled for 16 March 2014 to reflect this decision, which was condemned by the Ukrainian government, the United States, and the European Union.

Russia raised the number of their soldiers in Crimea to 30,000, according to the Ukrainian State Border Guard Service.

Russian troops seized the Crimean peninsula in a bloodless military takeover following the fall of Ukraine's government. This action was denounced by Moscow as an illegitimate coup.

Head of Euromaidan — Krym Andriy Shchekun was kidnapped in Simferopol.

Russian forces seized the main military hospital in Simferopol.

On March 11, 2014, the Supreme Council of Crimea and the Sevastopol City Council adopted a declaration of independence, citing the Kosovo independence precedent and paving the way for Crimea's potential annexation by Russia.

The multinational OSCE observation mission was denied entry to Crimea at gunpoint, and they reported evidence of Russian military presence near roadblocks.

Group of 7 world leaders stated they would not acknowledge the outcome of a referendum in Ukraine's Crimea region. They urged Russia to cease its support for the referendum on Crimea's status.

On March 14, 2014, the Crimean status referendum was deemed unconstitutional by the Constitutional Court of Ukraine, leading to the formal dissolution of the Crimean parliament by the Verkhovna Rada.

A US-sponsored resolution in the UN Security Council to reaffirm Ukraine's sovereignty, independence, unity, and territorial integrity was vetoed by Russia despite 13 council members voting in favor.

On March 16, 2014, a popular referendum was held in Crimea where the majority voted in favor of joining Russia. The vote was not recognized by Kiev and led to international condemnation and sanctions.

On 17 March 2014, following the referendum results, the Supreme Council of Crimea declared the formal independence of the Republic of Crimea, including the territories of the Autonomous Republic of Crimea and the city of Sevastopol. The parliament began nationalizing Ukrainian property and requested admission into Russia.

On March 18, Putin announced the 'joining' of Crimea to Russia. This move was met with condemnation from Western countries who considered the annexation illegal and imposed economic sanctions.

On March 19, 2014, Russian soldiers forcefully took over Ukrainian military bases in Crimea, escalating tensions between Russia and Ukraine.

Russian forces boarded and seized the Ukrainian corvettes Khmelnytskyi and Lutsk at Streletska Bay on March 20, 2014, as part of the escalating conflict in Crimea.

Russian President Vladimir Putin, along with officials from Crimea, signed an agreement for the Republic of Crimea to join Russia.

Russian forces took control of two Ukrainian air bases in Crimea. This marked a significant escalation in the conflict between Russia and Ukraine over the region.

Following the annexation, Russia introduced the rouble as the official currency in Crimea on 24 March, causing economic disruptions in the region.

The last Ukrainian military unit in Crimea, a minesweeper named 'Cherkasy', was seized by the Russian Armed Forces, marking the complete occupation of Crimea and Sevastopol.

Russian commander-in-chief announced that all military facilities around Crimea were under Russian control, and Ukrainian military personnel expressing loyalty to Ukraine were being evacuated from the peninsula.

The UN General Assembly approved a resolution declaring the Crimean referendum on 16 March as illegal, with majority of countries voting in favor of affirming Ukraine's territorial integrity.

On 29 March 2014, Crimea and Sevastopol switched to Moscow Time, aligning their time zone with Russia.

On 30 March 2014, Russia illegally annexed the Crimean Peninsula from Ukraine, marking a significant land-grab in Europe since the Second World War.

On March 31, 2014, Russia unilaterally denounced the Kharkiv Pact and Partition Treaty, citing the accession of Crimea and Sevastopol into Russia as the reason for the denunciation. Putin also formally rehabilitated various minority communities in the region that were ousted in the 1940s.

The Parliamentary Assembly of the Council of Europe deprived Russia of its voting rights in response to the situation in Crimea, indicating a diplomatic consequence.

On April 11, 2014, the Constitution of the Republic of Crimea and City Charter of Sevastopol were adopted, coming into effect the following day. This marked the establishment of new federal subjects in Russia.

On April 14, 2014, Vladimir Putin announced the opening of a ruble-only account with Bank Rossiya in Crimea. This move aimed to integrate the region economically and financially into Russia.

The Verkhovna Rada declared the Autonomous Republic of Crimea and Sevastopol to be under provisional occupation by the Russian military, imposing travel restrictions and affirming the territories as inalienable parts of Ukraine.

On 9 May 2014, an 'anti-extremist' amendment to the Criminal Code of Russia came into force, criminalizing incitement of violation of the territorial integrity of the Russian Federation, including calls for secession of Crimea. The offense was punishable by fines or imprisonment.

On 16 May 2014, the new Russian authorities in Crimea issued a ban on the annual commemorations of the deportation of the Crimean Tatars by Stalin in 1944, citing the 'possibility of provocation by extremists' as a reason. This ban led to defiance and commemorative rallies by the Tatar community.

Prime Minister Dmitry Medvedev signed a resolution establishing air, sea, road, and railway checkpoints along the border between Crimea and Ukraine, creating a legal framework for the checkpoint system.

During a visit to Crimea, Vladimir Putin stated that Russia would not push beyond Crimea and emphasized the need for a peaceful resolution to the conflict in Ukraine.

France and Germany brokered the Minsk agreements in September 2014, aiming to establish a ceasefire, withdrawal of heavy weapons, and special political status for eastern regions of Ukraine.

Tatar activist Edem Asanov disappeared on 29 September while traveling to work, adding to the list of over 18 Tatar activists missing since March. Some were allegedly abducted by government forces, raising concerns about human rights violations.

Ukraine created a Ministry of Information Policy to counteract Russian information aggression, aiming to address the spread of misinformation.

The Ukrainian parliament voted to set 20 February 2014 as the official date of the Russian temporary occupation of the Crimean peninsula, solidifying the recognition of the event.

The Ministry of Temporarily Occupied Territories and IDPs was established to manage regions affected by Russian military intervention in 2014, including Donetsk, Luhansk, and Crimea.

On August 8, 2016, Ukraine reported that Russia had increased its military presence along the demarcation line with Crimea. This led to tensions and military movements in the region.

On August 10, 2016, Russia claimed clashes with Ukrainian commandos resulting in casualties. Accusations of border infiltration and terrorism were exchanged between the two countries.

In 2017, a survey showed that a majority of non-Crimean Tatar respondents believed that if a referendum were held again, it would lead to similar results. This indicated the prevailing sentiment in Crimea post-annexation.

Lawmakers in the Ukraine Parliament overwhelmingly supported the imposition of martial law in response to the firing upon and seizure of Ukrainian naval ships by Russia near the Crimean peninsula.

Russia completed a high-tech security fence marking the de facto border between Crimea and Ukraine.

The UN General Assembly reaffirmed Ukraine's territorial integrity, condemned the 'temporary occupation' of Crimea, and reiterated nonrecognition of its annexation in a vote.

Ukraine launched the Crimea Platform, a diplomatic initiative aimed at protecting the rights of Crimean inhabitants and reversing the annexation of Crimea.