The relative good news is that an executive order signed by Mr. Obama gives his administration authority to act more expansively. Russian arms companies are subject to sanctions, as are “individuals and entities” that provide “material or other support to any senior Russian government official.” These authorities could be used to target key figures excluded from Monday’s designation; Putin’s defense minister and intelligence chief and the chairmen of the state gas, oil and railway companies ought to be on the sanctions list. Officials also have the power to hit any bank or other company that invests in Crimea or is found to undermine Ukraine’s sovereignty.

Mr. Obama has been holding back on tougher measures while offering Mr. Putin face-saving ways to de-escalate. While that is not an unreasonable policy, it can’t succeed if Mr. Putin is determined, as he seems to be, to crush Ukraine while ignoring Western reaction. It’s not too late to force Mr. Putin to reconsider his course, but that will require the West to get ahead of him in adopting measures that inflict real pain, rather than waiting to react to his next act of aggression.