( CNN ) Vladimir Putin lies . Blatantly . Publicly . And , apparently , without chagrin . But a year since the annexation of Crimea , what does that mean for the West 's ability to deal with him regarding Ukraine ? In February 2014 , `` little green men '' -- the Ukrainian term for professional soldiers wearing Russian combat fatigues but no identifying insignia -- seized key installations and checkpoints around Crimea . The Russian President 's website reported the following exchange at a March 4 , 2014 , news conference : . Question : `` The people who were blocking the Ukrainian army units in Crimea were wearing uniforms that strongly resembled the Russian army uniform . Were those Russian soldiers , Russian military ? '' Vladimir Putin : `` Why do n't you take a look at the post-Soviet states ? There are many uniforms there that are similar . You can go to a store and buy any kind of uniform . '' Question : `` But were they Russian soldiers or not ? '' Vladimir Putin : `` Those were local self-defense units . '' Within weeks , Putin admitted they were Russian troops . At the same news conference , Putin said he saw no possibility of Crimea joining Russia and said Moscow would do nothing to `` provoke '' that . Two weeks later , he presided as the Russian parliament passed legislation annexing Crimea . In a documentary shown on Russian television last Sunday , Putin said he gave the order to take Crimea on February 23 , 2014 . So , it is clear that Putin can and does lie . But with that in mind , how should Western leaders who must deal with him actually do so ? First of all , they should bear in mind Ronald Reagan 's `` trust but verify '' dictum . Second , while Putin may play fast and loose with the truth , he appears to be a rational actor who calculates costs and benefits . The challenge for the West is to structure agreements so that it remains in his interest to observe them . Take the 2010 New Strategic Arms Reduction Treaty , which limits U.S. and Russian strategic forces to no more than 1,550 deployed strategic warheads on 700 deployed missiles and bombers . The agreement requires data exchanges , notifications and on-site inspections . The Russians might be able to cheat a little , but not in a way that would give them a militarily significant edge without the United States having time to react . And the Kremlin has incentives to observe the treaty . If Russia violated it , the United States could relatively quickly add 1,000 strategic nuclear warheads to its deployed ballistic missile force . The U.S. government concluded last summer that Russia violated a 1987 treaty by testing a banned intermediate-range ground-launched cruise missile . As far as is publicly known , Moscow has not taken the more serious step of deploying the missile . Washington now seeks to persuade Russia to come back into full compliance and has threatened a variety of costs , including possible military countermeasures -- on top of the opprobrium of Russia 's European and Asian neighbors , who would be targeted by such a missile . ( It could reach little , if any , of the United States . ) The costs of noncompliance for Moscow could be significant . The question now topping the agenda is whether the West can trust any Russian promises regarding a settlement to the conflict in eastern Ukraine . Sadly , the track record offers little encouragement . Russia effectively did nothing to implement the first Minsk ceasefire , which was agreed to last September . It did not withdraw its military equipment or secure the Ukraine-Russia border . The Minsk II ceasefire reached in February fared little better at the outset . A Kremlin spokesman dismissed the idea that Russia was a party to the agreement -- even though Russia 's ambassador signed it . Russian forces backed those of the separatists attacking the Ukrainian town of Debaltseve in the first days after the ceasefire supposedly had begun . ( Putin 's continual denials that Russian troops are in eastern Ukraine have zero credibility after the Crimea case . ) Since then , the ceasefire seems to have taken better hold , though it remains fragile at best . At the same time , concern has grown that the port city of Mariupol could be the next separatist/Russian target . What can the West do to stabilize the ceasefire ? An assault on Mariupol ( or elsewhere in eastern Ukraine ) would probably trigger severe costs in the form of a new round of Western economic sanctions on Russia and the provision to Ukraine of greater military assistance , including defensive arms . As Hans Binnendijk and John Herbst recently suggested in The New York Times , the United States and European Union should tell the Russians now what costs would be imposed if there is an assault on Mariupol , in order to help deter such an attack . The West may not be able to trust Putin on the ceasefire in eastern Ukraine . But it can do more to raise the potential costs and affect his calculation , and hopefully dissuade him from further military action that would probably bring down the entire Minsk II agreement .
Russia annexed Crimea in last Sunday . Steven Pifer : Russia did nothing to implement the first Minsk ceasefire .