By D C Pathak New Delhi, Feb 28 : The prolonged Ukraine- Russia conflict resulting in President Putin ordering military action against the neighbouring country, has to be seen in the backdrop of three paradigm shifts that affected the US- Russia relations after the advent of Biden Presidency. The new US President reached out to NATO in a declared policy of reviving and banking on the strategic bonds with allies across the Atlantic whereas Donald Trump had de-emphasised EU, generally decried the tendency of the friendly countries to put the entire burden of security on America and welcomed Brexit as an event that enabled the UK to 'get back the country'. Secondly, Biden on assuming office put both China and Russia on notice as authoritarian states and warned them against indulging in any acts of aggression. His predecessor President Trump did not seem to have any issues with Putin notwithstanding the fact that Russia was sitting pretty on annexation of Crimea from Ukraine since 2014. Under President Trump a policy of strategic adjustment with Russia seemed to be in place with America focusing on China as the principal rival and adversary. Finally, the upswing in the activity of NATO to induct Ukraine into that military alliance, added to the economic and security concerns of President Putin who perhaps expected the world to recognise the need for him to ensure that the former Soviet states in its vicinity did not become hostile to Russia. The ongoing tension between Ukraine -- that leaned towards Europe under President Zelenskyy -- and Russia that had already tasted success on Crimean issue, led Putin to first militarily move -- in a projected 'defensive' stand -- in Donetsk and Donbas in the eastern provinces of Ukraine predominantly inhabited by Russian speaking population, to counter the 'suppression' inflicted by Ukraine government. Putin talked of 'peacekeeping' in these areas and then -- as President Zelenskyy pursued the objective of securing NATO membership to strengthen his hands -- declared his intention of extending military operations to the mainland of Ukraine. In what looked like a 'salami slicing' strategy -- China, a friend of Russia, has practised that in its own theatres of conflict -- Putin gave the impression of favouring the option of a satisfactory mediation in the midst of Russian military offensive in Ukraine. He had watched the US and its European allies threatening to put severe economic sanctions to get Russia to keep its hands off Ukraine -- these warnings did not unduly unsettle an astute observer of the current geopolitics like Putin who sensed that there was little likelihood of US sending its soldiers to Ukraine so soon after the messy withdrawal of American troops from Afghanistan and that the international community itself was against any 'war'. Putin must have assessed that he could extend military operations to the mainland of Ukraine to take swift control of Kyiv and achieve the objective of bringing about a regime change before withdrawing from there. The pattern of Russian intervention suggested targeting Ukraine's military assets to weaken Zelenskyy-Putin however, might be underestimating the Ukrainian will to resist the Russian onslaught. The armed conflict was getting protracted and its outcome was still unclear particularly after the move of US and its NATO allies to rush arms to Ukraine -- no commitment of boots on the ground had been made yet. (The writer is a former Director of Intelligence Bureau. The views expressed are personal) /IANS