"Chancellor Angela Merkel is now widely associated with the cease-fire, and to some degree Germany is seen as a key guarantor that the agreement will be maintained. Some German politicians have quietly indicated that they would need to reconsider their overall policy should a fundamental breach of the cease-fire take place. A major Russian separatist attack on Mariupol would represent such a breach and would trigger a major European policy review," the article reads.
"Given this reality, a coordinated trans-Atlantic initiative could both unite the West and deter Mr. Putin from pursuing what is likely to be one of his key goals - the creation of a land bridge from Russia to Crimea. A Western initiative - call it "the Mariupol test" - would require the United States to reach agreement with Germany and the rest of Europe now on how the West would react should Mr. Putin make a move against the city. It would require the Obama administration to press its European allies to unite and deter Mr. Putin's next move," the authors note.
"American and European leaders urgently need to construct a viable deterrent to Mr. Putin's plans for Novorossiya. This would not include NATO boots on the ground, since few in government or the public at large in Europe and America support that option. But any plan to contain Russia must be tough to be effective.
The article notes that "Washington and its European allies need to decide now what they will do should the separatist fighters and their Russian enablers who took Donetsk and Luhansk appear in Mariupol in force.
"Under such circumstances, Kyiv must be given lethal weapons and training, not just by the United States but by the Europeans as well. Tougher economic sanctions should also be imposed. The West should publicly discuss suspending Russia from the Brussels-based Swift financial-messaging system, a step which could cripple the already reeling Russian economy. Strict new limits on visas for Russian travel to the West should also be imposed. Such measures could ignite a dramatic reaction from Russia, such as a natural gas cut-off to Europe. But absent the will to introduce Western ground forces, it will take stern measures such as these to deter Moscow.
"Should the cease-fire hold and Ukraine regain full control of its territory, then the West may start to ease sanctions. Mr. Putin will need incentives for him to back down. That can be done without accepting what the Kremlin has gained through violence," Binnendijk and Herbst state.