MOSCOW  For hundreds of years, mariners have dreamed of an Arctic shortcut that would allow them to speed trade between Asia and the West. Two German ships are poised to complete that transit for the first time, aided by the retreat of Arctic ice that scientists have linked to global warming.

The ships started their voyage in South Korea in late July and will begin the last leg of the trip this week, leaving a Siberian port for Rotterdam in the Netherlands carrying 3,500 tons of construction materials.

Russian ships have long moved goods along the country’s sprawling Arctic coastline. And two tankers, one Finnish and the other Latvian, hauled fuel between Russian ports using the route, which is variously called the Northern Sea Route or the Northeast Passage.

But the Russians hope that the transit of the German ships will inaugurate the passage as a reliable shipping route, and that the combination of the melting ice and the economic benefits of the shortcut  it is thousands of miles shorter than various southerly routes  will eventually make the Arctic passage a summer competitor with the Suez Canal.