Azerbaijan has bought oil and natural gas from Russia to meet internal demand while exporting its own energy riches to the West. Russia also has been the main market for Azerbaijan’s fruit and vegetable exports. It also is a key transport corridor for Russia’s trade with Iran and other partners in the Middle East.

A cold snap has begun in Russian-Azerbaijani relations. And already the second in a year. In these conditions, it is worth considering whether such fluctuations in the political climate are accidental or natural,

The rift, provoked by the deaths of two ethnic Azerbaijanis in Russian custody, was the latest in a series of spats that revealed a deeper diplomatic rift between the former allies.