Russian President Vladimir Putin has mounted an aggressive propaganda campaign to convince his own people that someone else was responsible for the downing of Malaysian Airlines Flight 17 over eastern Ukraine. According to one version of this fantasy, Putin's own jet was in fact the intended target. According to others, downing the commercial airliner carrying 298 people was an American provocation to start a new world war.

But given the damning evidence already released that Ukrainian separatists -- puppets of the Russian government -- downed the passenger airline using a Russian-made surface-to-air missile, it's in Putin's best interest to drop this charade even though something like it became inevitable after he incited a civil war in Ukraine.

War is always a last resort. Leaders who initiate or enter wars take on grave responsibility. Combat creates conditions in which atrocities are likely -- even when leaders go out of their way to wage war as justly and humanely as possible, and even in wars waged by conventional forces scrupulously trained to follow international laws governing conflicts.

When Putin initiated the bloody hostilities in Ukraine, he did so without any serious justification, and also in an unconventional way that created greater risks. He relied on a heavily armed, largely unaccountable militia force. He apparently hoped to distance himself from the conflict, but in fact his deception heightens his culpability.

President Obama is right to demand answers from the Kremlin and to demand full access to the downed plane for international investigators -- regardless if the scene of this war crime has already been contaminated by those who committed it. Even setting aside the foreign policy implications, American citizens depend on the freedom of movement made possible by various treaties on international civilian aviation, so the United States has interests here. At the same time, Putin's increasingly bizarre behavior should teach Obama a hard lesson about his greatest foreign policy miscalculation -- his apparent belief, upon assuming office, that his own winning personality was all that had been missing from a positive “reset” to U.S.-Russian relations.

This error has already led to the abandonment of missile defense bases in Eastern Europe that might have proven useful -- especially given the likelihood that in retaliation for new sanctions, Putin will derail the current nuclear talks with Iran. It has led the U.S. away from neutrality in Syria's horrible Civil War and toward an ad hoc U.S. alliance with Bashar al-Assad, who apparently continues to use chlorine gas against his own citizens.

Americans probably should have been forewarned when wrong-way Obama ridiculed his 2012 election opponent for identifying Russia as a geopolitical foe. They should have been even more alarmed when Obama was overheard on a hot mic promising concessions to former Russian President Dmitri Medvedev, once the election was over and he had more “flexibility.” Even so, U.S. voters in 2012 chose a president who clearly trusted the Russians too much. Americans should now encourage him to do whatever it takes to undo the consequences of their mistake.