A NEW dish may soon appear in Moscow restaurants: “Belarusian” mussels. So goes a rather Soviet-style joke making the rounds since August 5th, when Russia blocked food imports from countries that have imposed sanctions on it. Seafood from America and Europe is now banned, but can still get into landlocked Belarus, which enjoys a customs-free zone with Russia. Many expect a return to the black-market smuggling of decades past.In March, when America and the European Union first introduced limited sanctions over Russia’s intervention in Ukraine, Russia’s official response was dismissive. Sergei Lavrov, the foreign minister, said Russia would not answer “hysterically” with retaliatory measures. But the far-reaching Western sanctions imposed last month—targeting state-controlled banks, among others—have forced Russia to respond.It is telling that whereas the West has largely stopped exports to Russia, such as technology for offshore oil exploration, Russia has blocked Western imports. Few Russian products are important to Western economies apart from oil and gas, and cutting those exports would mean fiscal ruin for Russian businesses and government. But Russia is a significant market for certain EU agricultural products, such as Polish apples and Norwegian fish. Some $ 9 billion-worth of goods is affected by the ban.Mr Putin’s move will hurt some European farmers. But the greater…