U.S. prosecutors have indicted five Russians and two American nationals accused of illegally obtaining sensitive U.S. technologies and ammunition for Russia’s military.

The seven defendants were affiliated with two Moscow-based wholesale machinery and equipment companies that operated under the direction of Russia’s Federal Security Service, or FSB, the successor agency to the Soviet KGB, according to a December 5 superseding indictment unsealed on Tuesday.

The two companies, Serniya Engineering and Sertal LLC. along with several others deemed “instrumental to the Russian Federation’s war machine” were sanctioned by the U.S. Treasury and Commerce departments following Russia’s February 24 invasion of Ukraine.

The indictment says Serniya headed an “illicit procurement network,” evading U.S. and Western sanctions “to acquire sensitive military grade and dual-use technologies, including advanced semiconductors, for the Russian military, defense sector and research institutions.”

The so-called “Serniya network” had been active since at least 2017, according to the indictment, with one defendant allegedly trying to smuggle into Russia as early as last month thousands of bullets used in sniper rifles.

To disguise the Russian government’s involvement and real identify of the end users, Serniya and Sertal operated a vast network of shell companies and bank accounts around the world, with Estonia, Finland, Germany and Hong Kong serving as the network’s main transshipment countries, according to the indictment.

The indictment comes as the United States and its allies seek to choke off Russia’s access to Western finance and technology by enforcing sweeping sanctions and export controls.

“The Department of Justice and our international partners will not tolerate criminal schemes to bolster the Russian military’s war efforts,” U.S. Attorney General Merrick Garland said in a statement. “With three of the defendants now in custody, we have disrupted the procurement network allegedly used by the defendants and Russian intelligence services to smuggle sniper rifle ammunition and sensitive electronic components into Russia.”

The two U.S. defendants, Alexey Brayman of New Hampshire and Vadim Yermolenko of New Jersey, were taken into custody earlier on Tuesday.

Vadim Konoshchenok, a suspected active FSB officer living in Estonia, was detained by Estonian authorities last week at the request of the United States and is awaiting extradition, the Justice Department said.

In October and November, Konoshchenok had been stopped at the Estonian-Russian border carrying cases containing thousands of U.S.-made bullets.

The four other Russian defendants — identified as Yevgeniy Grinin, Aleksey Ippolitov, Boris Livshits and Svetlana Skvortsova — remain at large.

“The FBI’s work, with our partners, to identify and stop illegal transfers of weapons and dual use-technology to Russia shows that we can and will reach around the world to keep Americans safe,” FBI Director Christopher Wray said in a statement. “The industries that these illegal transfers could support — quantum computing, hypersonic weapons — pose great danger in the hands of our adversaries.”

It is not clear whether the investigation predates Russia’s invasion of Ukraine. But the Justice Department said the probe was coordinated by Task Force KleptoCapture, an interagency law enforcement initiative launched following the invasion.

“We will continue the steady pace of seizures, indictments and arrests while the Kremlin is shopping for spare parts in North Korea,” Andrew Adams, director of Task Force KleptoCapture, said in a statement.

In an interview with VOA last week, Adams said the task force is leading dozens of investigations, with some predating the current Ukraine conflict.

According to the 16-count indictment, Ippolitov, a Russian national, served as a liaison between the two Moscow-based companies and the country’s defense and technology sectors.

Grinin and Skvortsova allegedly decided how to fulfill orders placed by the end users in the two sectors, according to the indictment.

Brayman and Yermolenko, the two U.S. nationals, facilitated the export of dual use items from the United States, with Brayman using his New Hampshire residence as a “trans-shipment point” to repackage and ship prohibited technologies to locations in Europe and Asia from where they would be trans-shipped to Russia, the indictment alleges. Brayman allegedly made at least four shipments of sensitive electronic test equipment and other dual-use items after Russia’s invasion of Ukraine.

Konoshchenok, who lived in Estonia, allegedly shipped, or physically smuggled U.S.-origin dual-use electronics, military-grade tactical ammunition and other export-controlled items from the Baltic nation to Russia.

In October, Konoshchenok was stopped at the Estonian border with 35 different types of semiconductors and other electronic components, as well as thousands of U.S.-made 6.5 mm (about 0.26 in) bullets used in military sniper rifles, according to the indictment.

In late November, he was again stopped at the Russian-Estonian border with approximately 20 cases containing thousands of U.S.-origin bullets, including tactical rounds and .338 military sniper rounds, according to the indictment.

The defendants face charges of conspiracy to defraud the United States regarding the enforcement of export controls and economic sanctions; conspiracy to violate the Export Control Reform Act (ECRA); smuggling; and failure to comply with the Automated Export System relating to the transportation of electronics.

If convicted of bank fraud or bank fraud conspiracy, the defendants face a maximum of 30 years in prison.

VOA’s Lynn Davis contributed to this article.

Editor’s note: The story has been updated with new information throughout, including additional details from the indictment.