ST.-NAZAIRE, France — Here on the Atlantic Coast, workers at France’s largest shipyard are closely following the standoff along Ukraine’s border with Russia, nearly 2,200 miles to the east.

“Of course, it raises questions here,” said Christophe Morel, a union delegate at the STX France shipyard, where two Mistral-class helicopter carriers are being built for the Russian Navy. The first, the Vladivostok, is due for delivery in just six months.

The timing couldn’t be worse. As workers were putting the finishing touches on the Vladivostok’s giant gray hull at a dock here last week, NATO warplanes were buzzing the alliance’s border with Ukraine in a show of force meant to deter any military intervention by Russia.

When France signed the contract for 1.2 billion euros, or $1.6 billion, with Moscow in 2011, these kinds of war games were nowhere on the horizon. At the time, French officials hailed the deal, the biggest military sale to Russia by a NATO country, as a sign that Moscow should be considered a partner, not an enemy. Now it has become an awkward showcase of the European Union’s vulnerability — even impotence — in the face of Russia’s moves against Ukraine.