The U.S. Department of Defense should drop a $900 million contract with Russian arms sales company Rosoboronexport to supply helicopters to Afghanistan's forces, if Moscow continues to arm the regime of Syrian President Bashar al-Assad, 17 senators have said in a statement sent to Pentagon head Leon Panetta, the Foreign Policy Journal reports.

"I am concerned that the U.S. Army is listed among the clients of Rosoboronexport. The United States has many alternative places to purchase helicopters, should we be rewarding Russia for its actions on Syria by buying their Mi-17s?" Senator John Cornyn said at a hearing on Thursday.

Cornyn and another senator, Dick Durbin, are the authors of the statement.

Army Chief of Staff Gen. Raymond Odierno pointed out in response, "there are no other options to meet the operational needs of the Afghan security forces. They are familiar with these helicopters and we are told that the Mi-17 is absolutely necessary to maintain the viability of the Afghan security forces."

Members of the lower chamber of the Russian parliament, the State Duma, said they were perplexed by the statement.

“A number of senators have recently made statements that seem strange at best. Possibly this statement is one of them,” said Irina Yarovaya, who heads the State Duma’s security and anti-corruption committee.

The Mi-8 and its uprated successor, the Mi-17 were used in great numbers by the Soviet Union during its war in Afghanistan, and by its client regime there. Many were left in the country after the Soviet withdrawal and used by the forces of the Mujahideen groups and the Taliban.

The most widely produced helicopter in history, the Mi-8/17 has earned a reputation for reliability and strength and is popular with the forces of many third-world nations.

Britain has been involved in training aircrew for the Mi-17 for the nascent Afghanistan armed forces.