NOBODY could accuse Sergei Glazyev of ambiguity. New Russian trade restrictions with Ukraine were a warning against the “suicidal” step of signing an association agreement with the European Union, said President Vladimir Putin’s chief economic adviser. And if it went ahead, the rules could become even tighter. For its part, the EU termed Russia’s stance “unacceptable”.Russia is making increasing efforts to deter the biggest country in its former empire from looking west and to prod it into joining the rival, Kremlin-led Eurasian Customs Union instead. As an EU summit in Vilnius in November nears, the means include soft power (talk of a shared Orthodox heritage), carrots (cheap gas and access to markets) and sticks (trade sanctions).Russia wielded the stick in July with a ban on confectionery produced by Roshen, a big Ukrainian company, allegedly because it contained carcinogens. This was odd: other customers had not complained. On August 14th Ukraine’s employers’ federation, whose members account for 70% of GDP, said stricter Russian customs procedures were paralysing trade. Russia accounts for a…