Vladimir Putin initially denied having anything to do with the seizure of Crimea in February 2014, when mysterious masked commandos in unidentified green uniforms seized the local parliament and spread across the entire peninsula.
These "little green men" marked the beginning of Russia's war against Ukraine, which culminated in a full-scale invasion in 2022.
The future of Crimea is now at the center of President Trump's peace plan and has led Ukrainian President Volodymyr Zelensky to rule out the possibility of recognizing Russian control over the peninsula.
The exact terms of Trump's plan have not been released, but reports suggest it will include US recognition of Crimea as a legal part of Russia. de jure in Latin.
For Trump, Ukraine's southern peninsula was "lost many years ago" and is not even "part of the conversation" in peace talks.
But for Zelensky, renouncing Crimea as an inalienable part of Ukraine would be unacceptable.
In the words of opposition MP Irina Gerashchenko, "territorial integrity and sovereignty is a red line for Ukraine and Ukrainians that cannot be crossed."
Trump's argument was "if Vladimir Zelensky wants Crimea so much, why didn't they fight for it 11 years ago when it was handed over to Russia without a shot being fired."
Few bullets were fired, but Crimea was occupied at gunpoint in a moment of power vacuum.
Putin later admitted that he masterminded the territorial grab in an all-night meeting with his officials days after Ukraine's pro-Russian leader was ousted from power in Kiev.
- The war changed Zelensky, is it time for another change?
- Trump calls Zelensky a 'dictator', says Russia has the upper hand
- Putin proposes direct talks with Ukraine
Crimea is a stumbling block for Trump
For an American leader in a hurry to conclude a peace agreement, Crimea could become a major stumbling block.
Trump is right when he says that there is little chance that Ukraine will regain Crimea in the foreseeable future, and he is realistic - de facto - under Russian control.
But that's a far cry from admitting that it's legal.
Zelensky is referring to the 2018 "Crimean Declaration" by Trump's then-Secretary of State Mike Pompeo.
Pompeo said America rejects "Russia's attempted annexation of Crimea" and pledged to continue to resist it until Ukraine's territorial integrity is restored.
Zelensky's implication is that Trump supported Ukraine on the Crimea issue then and should stick to it now.
If the seizure of territory not recognized by the international community is approved by the US as legal, what will that mean for international law and the principles of the United Nations Charter?
Weeks after the all-out Russian war began, there was an initial proposal from Istanbul to freeze the issue for later so that Russia and Ukraine could resolve it over the next 10-15 years.
The idea didn't catch on, but it was one way to overcome this stumbling block.
Zelensky constrained by the Ukrainian constitution
Zelensky firmly maintains that he has no authority to give up Crimea: "There's nothing to discuss here. It's against our constitution."
Article 2 of the Constitution states that Ukrainian sovereignty "shall apply to its entire "territory" which "within its present borders shall be indivisible and inviolable."
Any change to Ukrainian territory must go to a national referendum, which must be approved by the Ukrainian parliament.
It's not just President Trump who has problems with Kiev.
Russia also sees the Ukrainian constitution as an "obstacle" to peace efforts.
Constitutions can be changed, but not while Ukraine is in a state of war.
Recognizing Russia's illegal annexation would not only be a red line for Ukraine, but would also set a frightening precedent for countries like Romania, which borders the Black Sea.
The precedent would be felt far beyond the Black Sea.
Does Russia claim Crimea?
For historical reasons, Russians have long seen Crimea as part of their own territory, and Putin has spoken of a "living and indissoluble bond" with the peninsula, with its Black Sea resorts and balmy summer climate.
But Crimea, along with the rest of Ukraine, voted for independence from the Soviet Union during the country's collapse in 1991, and Kiev allowed Russia to lease the port of Sevastopol as a base for the Black Sea Fleet.
After its annexation in 2014, Putin sought to solidify Russian control over Crimea, first with a twenty-kilometer-long bridge built across the Kerch Strait in 2018, and then by seizing a land bridge along the coast of the Sea of Azov in 2022.
Putin believed he was righting an injustice done to Russia when Soviet leader Nikita Khrushchev awarded Crimea to Ukraine in 1954.
Russia, he said, "was not simply stolen, but plundered."
Crimea was first annexed by Tsarist Russia under Catherine the Great in 1783 and largely remained part of Russia until Khrushchev's decision.
Both Russia and Ukraine were Soviet republics so it wasn't a big deal for the Kremlin in 1954.
More than half of Crimea's population was Russian, largely because the original majority population, the Crimean Tatars, were deported under Soviet dictator Stalin in 1944.
Tatars were able to return to Crimea from exile only after 1989, when the Soviet Union began to disintegrate, and now make up about 15 percent of the Crimean population.
Russia hastily organized a referendum in March 2014, but the West dismissed it as a "charade," and the UN General Assembly adopted a resolution supporting Ukrainian sovereignty.
The International Criminal Court has ruled that Russia's activity in Crimea amounts to an "ongoing occupation."
Refat Chubarov, chairman of the Mejlis, the body representing the Crimean Tatars, insists that Ukraine must categorically reject any territorial concessions in exchange for peace.
"Crimea is the home of the indigenous people of the Crimean Tatars and an integral part of Ukraine," he said.
- "Where were you eight years ago" and "it's not that simple": How and why the Russians justify the war in Ukraine
- Putin declared four occupied Ukrainian regions "the territory of Russia"
- Tucker Carlson's interview with Putin: "The West deceived us"
Crimea may not be the only problem
Trump's peace plan has not yet been disclosed, but according to various reports and remarks by US officials, it can be concluded that Ukraine will be asked to agree to other difficult conditions.
Russian occupation of almost 20 percent of Ukraine would be de facto recognized behind the existing front lines, effectively freezing the conflict in four Ukrainian regions: Donetsk, Luhansk, Kherson and Zaporizhia.
This would be backed by "solid security guarantees," according to the American media outlet Axios, and likely supported by a "coalition of the willing," which includes the UK, France, but not the US.
It would have to be promised that Ukraine would not be admitted to NATO, although it could join the EU.
All American sanctions would be lifted, and economic cooperation with the US would be strengthened.
Axios also suggests that Russia would return a small part of occupied Kharkiv and allow Ukraine "unimpeded passage" along the Dnieper River, while the US would take control of the Zaporozhye nuclear power plant, which Russia seized in 2022.
And then there is the agreement between America and Ukraine on sharing mineral revenues, which is due to be signed by Ukrainian Prime Minister Denys Shmyhal.
- Ukraine and America reach agreement on rare minerals, say Kyiv
- Why does Trump want lithium from Ukraine when he has it in America?
- Putin offers America Russian and Ukrainian rare minerals
BBC is in Serbian from now on and on YouTube, follow us HERE.
Follow us on Facebook, Twitter, Instagram, YouTube i Viber. If you have a topic proposal for us, contact us at bbcnasrpskom@bbc.co.uk
Bonus video:
