But after weeks of bombardment, thousands of deaths and an exodus of millions of refugees, the question remains: what is his war aim and is there a way out?
Why has Putin invaded Ukraine?
The goals he set at the start of Russia's invasion appear to have been watered down during the course of a war that he assumed would be swiftly won. He could not even admit it was an invasion or a war, preferring the fiction of a "special military operation".
But what is clear is that he sees this as a pivotal moment in Russian history. "Russia's future and its future place in the world are at stake," says foreign intelligence chief Sergei Naryshkin.
The Russian leader's initial aim was to overrun Ukraine and depose its government, ending for good its desire to join the Western defensive alliance Nato.
He told the Russian people his goal was to "demilitarise and de-Nazify Ukraine", to protect people subjected to what he called eight years of bullying and genocide by Ukraine's government. "It is not our plan to occupy the Ukrainian territory. We do not intend to impose anything on anyone by force," he insisted.
But there were no Nazis and no genocide, and Russia has imposed brutal force on dozens of towns and cities and united Ukrainians in opposition to its occupation.
The bombardment continues - but latest reports from peace talks suggest Russia is no longer seeking to overthrow the government and is instead aiming for a neutral Ukraine.
Why Putin wants a neutral Ukraine
Since Ukraine achieved independence in 1991, as the Soviet Union collapsed, it has gradually veered to the West - both the EU and Nato.
Russia's leader aims to reverse that, seeing the fall of the Soviet Union as the "disintegration of historical Russia".
He has claimed Russians and Ukrainians are one people. "Ukraine never had a tradition of genuine statehood," he asserted, denying Ukraine its history.
In 2013 he pressed Ukraine's pro-Russian leader, Viktor Yanukovych, not to sign a deal with the European Union, prompting protests that ultimately ousted the Ukrainian in February 2014.
Russia retaliated in 2014 by seizing Ukraine's southern region of Crimea and triggering a rebellion in the east, backing separatists who have fought Ukrainian forces in an eight-year war that has claimed 14,000 lives.
There was a ceasefire, and a 2015 Minsk peace deal that was never implemented. Just before his invasion, President Putin tore up the peace agreement and recognised two Russian-backed statelets as independent from Ukraine.
As he sent in the troops, he accused Nato of threatening "our historic future as a nation", claiming without foundation that Nato countries wanted to bring war to Crimea.
Is there a way out of this war?
Ukrainian presidential adviser Mykhailo Podolyak believes a ceasefire could start in the coming days because Russian forces are stuck in their current positions.
Both sides have spoken positively of progress in negotiations, and Mr Podolyak says Russia's president has softened his demands.
At the start of the war, the Russian leader wanted Ukraine to recognise Crimea as part of Russia and to recognise the independence of the separatist-run east. Ukraine would have to change its constitution to guarantee it would not join Nato and the EU.
The future status of Crimea and the Russian-backed statelets in Luhansk and Donetsk is still far from being resolved, but they may not be a deal-breaker if the two sides agree to address that issue at a later date.
What are Ukraine's demands?
Ukraine's requirements are clear, says the presidential adviser: a ceasefire and the withdrawal of Russian troops, but also legally binding security guarantees that would give Ukraine protection from a group of allied countries that would actively prevent attacks and "take an active part on the side of Ukraine in the conflict".
Securing Russian military withdrawal to pre-war positions will not only be a Ukrainian demand, it will also be a red line for the West, which will refuse to accept another of Russia's "frozen conflicts", says Marc Weller, professor of international law and former UN mediation expert.
Ukraine has also softened its stance since Russia's invasion, with President Zelensky saying that Ukrainians now understood that Nato would not admit them as a member: "It's a truth and it must be recognised."