Russian president Vladimir Putin shows every intention of keeping the world guessing about his ultimate intentions in Ukraine.
An apparent escalation of violence in eastern Ukraine has raised fears that the current conflict will broaden beyond fighting between the Kiev government's forces and separatists, even though the evidence suggests Moscow is not contemplating a major intervention.
Reports have estimated that the numbers of troops taking part in a recent series of military exercises near the eastern Ukrainian border have reached as many as 40,000. While this demonstrates that Russia is able to deploy a sizeable ground force, the troops available are insufficient to subdue a country as large as Ukraine. Mr Putin does, however, retain the option of launching a limited operation to keep the Ukrainian military off-balance and possibly even establish a separatist state.
On Friday, the Ukrainian government claimed to have used artillery fire to destroy a number of Russian vehicles that had entered its territory. Moscow immediately denied that any of its vehicles were involved. This rebuttal was somewhat undermined on the following day when Alexander Zakharchenko, the self-appointed leader of the "Donetsk People's Republic", claimed in a video posted by the rebels on YouTube that they were being reinforced by 1,200 troops specially trained in Russia along with 150 armoured vehicles. In addition, a 270-strong convoy of Russian lorries carrying "humanitarian aid" for citizens trapped by the conflict remained stuck at the border pending an agreement between Moscow and Kiev that would allow it to cross.
In a speech in Yalta on the previous day, Mr Putin surprised his audience with conciliatory remarks about his wish to defuse the conflict in eastern Ukraine. Perhaps more tellingly, the speech was not given the extensive live coverage normally expected for a presidential address and was only broadcast in edited form with a voice-over. It is likely that the distribution of Mr Putin's message was limited to prevent domestic criticism that he was softening his position on Ukraine. Shortly before Mr Putin made his remarks in Yalta, Vladimir Zhirinovsky, the deputy speaker of the Russian Duma and a prominent extreme nationalist, publicly called for the re-establishment of Russia's empire and for Mr Putin's title to be changed from president to "supreme leader".
Although Mr Putin made it clear in Yalta that Mr Zhirinovsky's comments did not reflect official policy, the strategic rationale behind Russian policy remains consistent. The Kremlin remains willing to accept a deteriorating relationship with the West as a price worth paying to defend its interests. Mr Putin has reaped high opinion poll ratings for pursuing his aggressive policy in Ukraine in the face of concerted international pressure. His Yalta speech can be interpreted as either a genuine attempt to reassure the international community, or a calculated ploy to distract attention from continued covert assistance to the rebels.
Mr Putin suspects that if Russia accepts any negotiated solution to the current crisis, this will reduce his policy options for the future. The Russian president and his inner circle are determined to draw the former Soviet republics closer together and resist western encroachment. In his quest for the creation of a "Eurasian Union", Mr Putin has reached agreement with Belarus and Kazakhstan and hopes also to enlist Kyrgyzstan, Tajikistan and Armenia. Ukraine, however, remains the key. Mr Putin is reported to have told former US president George W Bush at a Nato summit in Bucharest in 2008 that "Ukraine is not even a state" and that while "part of its territories is Eastern Europe", the "greater part is a gift from us".
For the moment, Western nations must hope that diplomatic pressure can dissuade Moscow from further intervention. Nato expressed its alarm at the latest Russian "incursion", while the White House called the move "extremely dangerous and provocative". There is little that the Nato countries can do for Ukraine itself beyond supplying further economic assistance and non-lethal aid to the Ukrainian military. Further action against Russia would involve enhanced sanctions and exclusion from international organisations. A Nato summit in the UK next month could see agreement on new measures, such as the dispatch of military training missions to help Ukraine, though it would be some time before such assistance could take practical shape.
If there is any will to de-escalate the conflict remaining among the major powers, then all parties have to work hard to rebuild trust. The Obama administration has repeatedly claimed that the Russian government's promises to help with reining in the separatists have been accompanied by more clandestine arms deliveries to the rebels. The sense that the crisis is intensifying has been reinforced by the significant gains made by the Ukrainian military in recent weeks. The Kiev government claims that it is ready to subdue the last remnants of the separatist resistance in the eastern cities of Donetsk and Luhansk.
If Mr Putin is set on raising the stakes in Ukraine, then he cannot allow the rebels to be defeated. There is hope that some progress might result from Sunday's talks between the foreign ministers of Russia, Ukraine, Germany and France in Berlin. Despite Mr Putin's soothing words in Yalta, deep-rooted suspicions of Russia's intentions in Ukraine mean that any diplomatic attempt to pacify the current situation will be a fraught and lengthy process.
Stephen Blackwell is an international politics and security analyst

Putin is prepared to alienate the West to suit his agenda
Stephen Blackwell asks: is Russia going to let eastern Ukraine out of its grip or is Putin willing to incur western sanctions in pursuit of his Eurasian union?
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