Homeland Security Investigations (HSI) is the lead U.S. agency dedicated to stopping hostile nations (like Russia, China, Iran, and North Korea), terrorist networks, and criminal organizations from illegally acquiring advanced U.S. weapons and defense technology.

The U.S. relies on strict export controls and sanctions to keep its highly sought-after military innovations out of the wrong hands. When bad actors successfully smuggle this technology or bypass sanctions, it not only renders those international penalties useless but also puts U.S. troops at direct risk of facing American-made technology on the battlefield.

Because HSI is the only U.S. government agency with the full legal authority to enforce all export control laws, they focus heavily on investigating crimes, protecting American strategic superiority, and completely dismantling the illicit supply chains used by adversaries.

They lead several specific initiatives to get this done:

Project Shield America (PSA): An outreach initiative that builds partnerships with private tech industries and universities to help them spot and prevent the theft of sensitive, dual-use technology.

Export Enforcement Coordination Center (E2C2): An HSI-directed hub that improves communication and teamwork between law enforcement, the intelligence community, and agencies that issue export licenses.

Task Force KleptoCapture: A Department of Justice task force where HSI plays a major leadership role in enforcing the massive economic sanctions and export controls placed on adversaries by the U.S. and its allies.

You can get more info from official statement.