At some point the West's warnings will have to become deeds, part of the problem is they don't know which Putin they're dealing with.
Rugged Russian President Vladmir Putin visited a centre for endangered Persian leopards at Sochi National Park.
These are difficult days for Ukraine, a country edging toward its second revolution in a decade.
The Prime Minister has reacted to President Vladimir Putin signing a treaty to make the Crimea region part of Russia.
The steps taken by President Putin today to attempt to annex Crimea to Russia are in flagrant breach of international law and send a chilling message across the continent of Europe.
Britain depends on the stability and security of the international order. That relies on a rules based system where those who ignore it face consequences. And that’s why the EU and the United States have already imposed sanctions.
– David Cameron
It is completely unacceptable for Russia to use force to change borders, on the basis of a sham referendum held at the barrel of a Russian gun. President Putin should be in no doubt that Russia will face more serious consequences and I will push European leaders to agree further EU measures when we meet on Thursday.
The choice remains for President Putin: take the path of de-escalation or face increasing isolation and tighter sanctions.
Foreign Secretary William Hague says he regrets President Vladimir Putin has chosen "the route to isolation" by moving to incorporate Crimea into Russia.
President Vladimir Putin told parliament that Western attempts to frighten Russia with sanctions over its takeover of Ukraine's Crimea region would be viewed as an act of aggression, and that Moscow would retaliate.
President Vladimir Putin and two Crimean leaders have signed a treaty that makes Ukraine's Crimea region part of Russia.
The signing follows a speech by the president to the Russian parliament.
During an address to the Russian parliament, President Vladimir Putin said relations with the "brotherly" Ukrainian people will always be of crucial importance to Russia.
"Relations with Ukraine and the brotherly Ukrainian people have always been, remain, and will always be most important and crucial for us, without any exaggeration," Putin said.
He also condemned "so called" authorities in Ukraine, saying they had conducted a state coup and "will do anything for power".
After President Putin signed a decree recognising Crimea as a sovereign state William Hague has said the referendum was not legitimate and its outcome was not legal.
The Foreign Secretary said:
We are witnessing a clear attempt to pave the way for the annexation of part of the sovereign territory of an independent European state, through military force and an illegal and illegitimate referendum.
The UK calls again on Russia to enter into dialogue with Ukraine and with the international community to resolve this crisis through diplomacy and in accordance with international law, not to exacerbate it further through unilateral and provocative actions.
Continuing to ignore those calls will bring serious consequences for Russia. We will urgently consider our response to this latest escalation with our allies and partners, including at the European Council this week.
Vladimir Putin has told President Obama in a telephone conversation that today's referendum in Crimea is compliant with international law, a Kremlin spokesman has said.
The Russian President also told his American counterpart that observers from the Organisation for Security and Co-operation in Europe (OSCE) should be deployed all over the Ukraine.
The two men also agreed that, in spite of their countries' differences of opinion, they should work together to stabilise the situation.
Vladimir Putin has told Angela Merkel an upcoming referendum in Crimea is in accordance with international law.
In a phone call between the two leaders, Putin said the actions of the Crimean parliament were aimed at protecting the legitimate interests of the population in the peninsula.
A statement from the Kremlin added that, while Putin and Merkel differed in their view on the situation in Ukraine, they were agreed that a de-escalation of tensions should be achieved as soon as possible.
Russian President Vladimir Putin's efforts to de-escalate the crisis in Ukraine have been met with no understanding, his spokesman said.
Dmitry Peskov said: "Regardless of all the efforts of our president, his readiness to explain Russia's position practically on a daily basis, we still hit a wall of no understanding.
"It is rather sad and what is worse is that it is very bad from the point of view of possible repercussions."