Pentagon Press Secretary George Little said this week that the department would respond to Cornyn, but he defended the contract.

“The Mi-17 helicopter, from our vantage point, is . . . about equipping the Afghan air force with what they need to ensure that they have the capabilities from an air standpoint to defend themselves,” Little said.

The Afghans have a long-time familiarity with the Russian-made equipment, arguably making the Rosoboronexport buy a cheaper option than U.S.-made helicopters. But defense expert Loren Thompson of the Lexington Institute, a Washington-area research center, said: “Cornyn is raising valid questions about where the U.S. buys its weapons. There’s no question Bell and Sikorsky and Boeing could supply world-class helicopters for the Afghanis.”

Texas has several helicopter operations, including Bell Helicopter Textron and Sikorsky.

Defense experts said the United States had a key interest in seeing Rosoboronexport fulfill its contract to supply Afghan forces.

“If you’re trying to help the Afghans, we’re trying to get along with the Russians in Afghanistan, and (taking action on Rosoboronexport) complicates the exit strategy,” said Michael O’Hanlon, a senior fellow at the Brookings Institution, another Washington-area research center. “I’m not defending the buy, but we have an interest in the Afghans getting the helicopters quickly. We make very good helicopters, but they are more expensive and the Afghans are used to the Russian ones.”

Russia expert Stephen Blank of the U.S. Army War College in Carlisle, Pa., agreed that while the United States could express anger with Russia in other ways, the Pentagon shouldn’t kill the Afghanistan contract. Selling the Mi-17s to the Afghans, he said, “makes perfect economic sense” and despite “the knee-jerk reaction of some senators, depriving them of helicopters benefits nobody.”

Human Rights First, an advocacy group, argues that the Pentagon should end the contract.

“We cannot allow deals with Rosoboronexport to get lost in the shadows of defense contracts and procurement. It’s increasingly frustrating to hear the administration claim one position only to discover that its actions run counter to it,” said Sadia Hameed, the director of the group’s Crimes Against Humanity program

“They need to shine a light on defense purchases to reassure the American people that they are not buying weapons from a company that is enabling the massacre of thousands of Syrian men, women and children,” Hameed said.