Work has begun on the construction of an ambitious gas pipeline project linking Russia and Germany via the Baltic Sea.
The link will deliver Russian gas to Germany - and eventually to other Western European nations - by 2010.
But the 1,200km (744 mile) pipeline is not without controversy.
It is set to bypass Poland and Ukraine, prompting concern from both countries that they will be cut off from Russian gas supplies.
Russian Prime Minister Mikhail Fradkov and German Economy Minister Michael Glos attended a launch ceremony on Friday in the northern Russian town of Babayevo, watching the symbolic welding of two pieces of pipeline.
"Today we have launched a great European project... This is a new export route that will increase Europe's energy security," said Alexey Miller, chairman of Russian gas giant Gazprom.
The pipeline will run from Babayevo to the Russian coast at Vyborg before going under the Baltic Sea to the town of Greifswald in north-eastern Germany.
The $5bn (£2.7bn) deal was struck between the two countries' leaders last September, just before German Chancellor Gerhard Schroeder lost power.
Russia is one of Western Europe's biggest suppliers of commodities and supplies a quarter of the region's gas needs.
With limited natural resources of its own, Germany's dependency is even greater and Europe's biggest economy relies on Russia for a third of all its oil and gas imports.
But the deal rang alarm bells in Warsaw and Kiev, who fear it will compromise their own energy security.
They are currently billed at below the market rate for their gas supplies, because they allow Russian exports to cross their territories.
Poland - with its historic grievances against Germany and Russia - is suspicious of both nations. Recent disagreements with Moscow have created a prickly nationalist mood in Warsaw, says the BBC's Andre Vornic.
Kiev, for its part, feels it is being punished by Russia for leaving Moscow's orbit and moving closer to the West last year, our correspondent adds.