Weak growth in peers
Germany is also suffering from ongoing weak demand in many of its euro zone neighbors. The region's gross domestic product (GDP) came in flat—below expectations—in the second quarter, and its real GDP is still around 2.5 percent below its pre-crisis peak—and 5 percent below if Germany is excluded, according to BNP Paribas.
The country's very open economy makes it highly vulnerable to low demand in other countries. Exports account for around half of German GDP, and while trade with China and other emerging markets is rising, Germany's major partners remain European—notably, France, the U.K., Austria and Italy.
"The external trade sector will contribute very little to growth over the next few quarters," warned Evelyn Hermann of BNP Paribas in the bank's September "Global outlook" report.
Meanwhile, ING's Brzeski noted: "Downside risks for the German economy currently do not mainly come from geopolitical tensions but rather from longer-than-expected weak demand from euro zone peers."
Euro zone exports to Russia have fallen since early 2013 in euro terms, driven partly by the Russian Federation's economic straits, but mostly by the ruble exchange rate.
Trade has fallen further this year, following Russia's incursion into Ukraine and the tit-for-tat sanctions by the West and Moscow that have followed. Russia has restricted food imports, while Europe and the U.S. have cut Russian state-owned companies' access to finance and frozen some leading politicians' assets.
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In the first six months of this year, German exports to Russia fell 13 percent on the same period in 2013. This is problematic because Germany has strong economic ties with Russia—2 percent of its GDP is directly exposed to the country, according to BNP Paribas.
The crisis has also hit Germany's trade with eastern Europe, which buys around 10 percent of German exports, and business with other nearby emerging markets, like Turkey.
Business confidence in Germany has also taken a knock. The widely watched Ifo Business Climate Index fell for a fifth consecutive month in September to its lowest level in nearly 1-1/2 years.
"Increased (geopolitical) tensions could derail German growth more than we expect," warned BNP Paribas's Hermann.