IN RECENT years Germany has become Poland's closest political ally and economic partner. The heads of state, heads of government and foreign ministers of the two countries are on excellent terms and see each other frequently. But in the last few months this new closeness has been put to a test as Berlin's conciliatory policy towards Russia over the escalating crisis in Ukraine is provoking increasingly loud grumbles in Warsaw. Polish officials are concerned that Germany is too keen to end the conflict in Ukraine on Russia's terms, and is reluctant to impose tougher economic sanctions on Russia and to shift NATO forces to the east. The latest salvo comes from Roman Kuzniar, foreign-policy adviser to Bronislaw Komorowski, Poland's president. In a toughly worded column in Rzeczpospolita, a daily, Mr Kuzniar denounces western European governments for refusing to stand up to the Russian president, Vladimir Putin, accusing them of appeasement. “Putin is paralysing their freedom of action in the same way that a snake in the desert paralyses a rabbit,” he writes, before taking special care to castigate Germany. “We have to accept that, because of Berlin's specific relationship with Russia, we cannot count on Germany in matters of regional security,” he writes, adding that Germany is treating Russia “like a special needs child who has to be raised without stress”.

The tone marks a sharp break from the recent warmth between Poland and Germany. The two countries are partners in the European Union. Their economies are closely intertwined, with low-cost Polish factories making car parts, electronics and other components that power the mighty German export machine.

The foreign ministers of the two countries took the lead in negotiating an end to the bloodshed in Kiev's central square, Maidan, earlier this year. But as the scope of the Ukrainian crisis is growing, Poland and Germany are increasingly taking diverging views. Poland (and the three Baltic countries) is very alarmed about Russia's regional ambitions, fearing a return to the imperial policies that made it a Russian colony for most of the last three centuries. Germany has for years been trying to modify Russian behaviour through a policy of economic engagement. But so far the main result has been to tie German business ever more closely to Russia whereas the Kremlin's course has hardly changed. Trade between Germany and Russia amounted to €76.5 billion ($101 billion) last year, not far off the €71.5 billion of trade between Germany and Poland.

Comments like those from Mr Kuzniar are designed to send a message to Germany, says Olaf Boehnke, head of the Berlin office of the European Council on Foreign Relations. This is an attempt by the Poles to push Germany into a stronger confrontation with Russia,” he says. But while Mr Kuzniar's grumbles may not succeed in changing Germany's policy, the increasingly brazen Russian intervention in Ukraine may, in the end, drive Berlin to take a tougher line with Moscow.