The United States and Britain are enacting sanctions to target an Iranian transnational assassinations network, the U.S. Treasury Department said on Monday.

The network is led by Iranian narcotics trafficker Naji Ibrahim Sharifi-Zindashti and operates at the instruction of Iran’s Ministry of Intelligence and Security (MOIS). The network targets Iranian dissidents and opposition activists at the direction of the Iranian government.

Zindashti’s network has carried out numerous acts of transnational repression against dissidents, journalists, activists, and former Iranian officials to silence the Iranian regime’s perceived critics. This includes assassinations, kidnappings and hacking operations across the Middle East, Europe and North America. The Iranian government utilizes organized criminal groups to conceal its connection to the said killings and kidnappings.

“The Iranian regime’s continued efforts to target dissidents and activists demonstrate the regime’s deep insecurity and attempt to expand Iran’s domestic repression internationally,” said Brian E. Nelson, undersecretary of the Treasury for Terrorism and Financial Intelligence. “The United States, alongside our international allies and partners, including the United Kingdom, will continue to combat the Iranian regime’s transnational repression and will utilize all available tools to stop this threat, especially on U.S. soil.”

The U.S. Treasury is authorized under Executive Order 13553, which allows sanctions because of serious human rights abuses by the Government of Iran. The MOIS has been recognized as complicit in serious human rights abuses for its actions against the Iranian people since 2009. The network has also been designated as a supporter for terrorist groups such as Hamas, Hezbollah and al-Qaida.

Following Monday’s announcement, the sanctions block and report all property and interests in property owned by individuals connected to MOIS currently in the United States or under the possession or control of U.S. persons to the Office of Foreign Assets Control.

The U.S. Treasury said its action was being taken in conjunction with the unsealing of an indictment by the Justice Department and Federal Bureau of Investigation.

Some information for this report was provided by Reuters.