U.S. Republican Senator Richard Lugar has requested the Congressional Research Service (CRS) to scrutinize the sale of armaments by NATO member states to Russia, the Atlantic Council, a Washington-based think tank, said on its website on Wednesday.

In his letter to the CRS, Lugar in particular expressed concerns over Russia’s recent contract with France, under which French shipbuilder DCNS will build two Mistral class amphibious assault ships for Russia’s Navy.

Lugar, a top member of the Senate Committee on Foreign Relations, is apparently concerned that Russia may use some weapons against the interests of the United States or its partners. He asked the CRS to draft a relevant report by April 20.

Russia and France signed a $1.7 billion contract on two French-built Mistral class amphibious assault ships for the Russian Navy, which includes the transfer of sensitive technology, in June 2011. The helicopter carriers are due to enter service with the Northern and Pacific fleets in 2014 and 2015.

A Mistral-class ship is capable of carrying 16 helicopters, four landing vessels, 70 armored vehicles, and 450 personnel.