For once, matters may be largely out of the Russian leader's hands: he appears to have little left in his political armoury to woo Ukraine, especially if the protesters oust President Viktor Yanukovich or persuade him to change tack again.
There is no sign of Yanukovich quitting. But rallies by about 350,000 people this weekend, at times marred by clashes, have unleashed democratic forces which, for all his political calculations, Putin cannot control.
Public threats, such as cutting off gas supplies to Ukraine which could disrupt onward supplies to Europe, would risk stirring anti-Russian sentiment and do Yanukovich no favours.
"Yanukovich's big 'nyet' to EU followed by brutality against protesters could trigger Orange Revolution 2.0, wiping smirk off Putin's face," Strobe Talbott, a former U.S. deputy secretary of state, said in a tweeted message.
Talbott was referring to the "Orange Revolution" against sleaze and fraud which kept Yanukovich out of power in 2004.
Under pressure from Russia, Yanukovich dropped plans to sign a free trade pact with the European Union last Friday that would have steered his country of 46 million closer to Europe and further out of the orbit of its former Soviet masters in Moscow.
Instead he decided to rebuild economic ties with Russia. The sweeteners offered by Russia are thought to include cheap credits, cut-price Russian gas and trade incentives, and few doubt Putin also threatened Kiev with crippling trade sanctions.
It was a victory for Putin, but one which could yet prove pyrrhic - obliging Russia to support Ukraine financially when its own economy is stuttering - or be reversed.
Putin may be able to do little more now than offer even better terms to Yanukovich than those agreed in secret to try to prevent another policy zig-zag by Kiev.
DREAMS OF BIG UNION THREATENED
Putin is unlikely to stop pushing Ukraine to join a Moscow-led customs union with Kazakhstan and Belarus which he hopes to develop into a political and economic "Eurasian Union" to match the might of the United States and China.
Without Ukraine, its huge market, rich mineral resources and proximity to the EU's borders, building the Eurasian Union into a major alliance is probably mission impossible for Putin.
"Russia's policy is, in fact, an important question mark now. Moscow succeeded in scuttling Ukraine's attempt to draw closer to the EU, but Moscow's firmly stated longer-term goal of getting Ukraine to join the customs union is now also distinctly less attainable," said Alex Brideau, a senior analyst at the Eurasia Group risk consultancy.
He said Moscow was unlikely to drop membership of the customs union as the main condition for granting Ukraine loans and reducing the price it pays for Russian gas.
"We continue to believe that Moscow will, for now, stick to its conditions on bloc-membership," he said.
Ukraine's government must find more than $17 billion in 2014 to meet gas bills and debt repayments. Including the private sector, Ukraine faces debt repayments of more than $60 billion, or a third of its gross domestic product.
Putin is banking on Yanukovich not being able to obtain enough money from other sources to pay the bills, making him dependent on Russia stumping up the cash. The International Monetary Fund has no loan programme with Ukraine.
For his part, Yanukovich continues to shop around for the best deal, playing East off against West. He was heading for China on Tuesday in his search for funding and investment, at the same time sending a signal to Putin that he cannot be complacent in the battle over ties with Ukraine.
Ukrainian leaders have also said the decision to freeze moves towards Europe is just a "pause" forced on then by economic necessity and have left their options open.
PROTESTERS SAY 'NO TO USSR'
Putin will for now continue efforts to shore up the customs union and aim criticism at the EU and the Ukrainian protesters, partly to show his domestic audience that he is defending Russian interests.
On Monday, he described the protesters as "very well prepared and trained militant groups" engaged in an attempt to unsettle Ukraine's legitimate rulers, and hinted that they had been trained by outside actors.
It is typical of Putin to seek to deflect such problems on to the West and often, by implication, the United States.
But a visit on Monday to Armenia, where he made the comments, showed the problems he faces winning public support in persuading other former Soviet republics to bond again with Moscow again, more than two decades after the Soviet Union collapsed.
His visit to Armenia was intended to ensure the southern Caucasus country carries out its promise to join the customs union, secured at talks with Putin in September which turned Yerevan away from its pro-European course.
But hundreds of people protested against Putin's visit under banners declaring "Putin, go home" and, in a reference to the Eurasian Union, "No to the USSR".
For all his success in putting pressure on politicians to bend to his will, Putin may not yet have come to terms with "people power".
He also appeared to be caught off guard in 2011 when he ran into opposition and protests in Russia after his announcement that he planned to return to the presidency after four years as prime minister.
Military might, even as a last resort, is an unlikely option for Putin as it would risk a Western military response and all-out confrontation, even though Russia fought a brief war with Georgia in 2008 over two breakaway regions with big ethnic Russian populations.
"I have no information whatsoever that Russian troops should be prepared to enter Ukraine," NATO Secretary General Anders Fogh Rasmussen told reporters in Brussels, when asked about speculation that Moscow could be ready to send in troops.
But he added: "In that case, of course, it would be in contradiction of all international obligations."
* Mass protests against Yanukovich's U-turn
* Putin wants to lure Ukraine into customs union
* Protests could undermine Putin's triumph