Sen. Mitt Romney is among a group of bipartisan senators who want greater oversight of what exports are shipped from the United States to other countries, over concerns some U.S. technology is ending up in weapons used by countries like Russia.

A CNBC report last year showed U.S. microchips are ending up in Russian weapons like drones, missiles and armored vehicles after taking a circuitous route through other countries before finally landing in Russia.

Romney introduced legislation with New Hampshire Sen. Maggie Hassan, a Democrat, that would increase oversight over exports through the Export Enforcement Coordination Center.

“This center should be the heartbeat for export controls coordination. Our legislation would help ensure that agencies are talking to each other and working with the private sector and foreign partners to keep sensitive technologies from going to U.S. adversaries,” Romney said at a Senate hearing this week.

Romney raised concerns that even with controls in place over certain exports, weapons components are “still falling into the hands of our adversaries.”

“For example, U.S. and EU exports reportedly increased significantly to central Asian countries that in turn are increasing their exports to Russia. There are real concerns that Western technologies are making their way to our adversaries,” he said in his opening statement.

At the hearing, the Department of Commerce announced new limits on Chinese companies, as well as companies from other countries that were suspected of funneling weapons components to Russia and Iran.

In response to a question from Romney about the volume of exports, James Mancuso, an assistant director at the U.S. Department of Homeland Security, said the “sheer volume of legitimate trade far outweighs the illicit trade that’s going on.”

“However, that small slice is of concern,” he said.

Those providing oversight over this issue are “laser focused on retaining America’s innovation, our creativity, our intellectual property right,” he said. “We develop the most advanced weapons systems in the world because of our ability to create this. We are the envy of the entire world. That also means our adversaries will stop at nothing to obtain this technology in these weapon systems.”