The U.S. imposes new sanctions to cut off funding to Iran-backed militant groups.

The United States on Tuesday imposed sanctions on nearly 50 entities and people that it said were part of an Iranian operation to direct billions of dollars toward terrorist organizations, including Hamas, Hezbollah and the Houthis.

“The United States is taking action against a vast shadow banking system used by Iran’s military to launder billions of dollars of oil proceeds and other illicit revenue,” Wally Adeyemo, the U.S. deputy secretary of the Treasury, said in a statement.

“We will continue to pursue those who seek to finance Iran’s destabilizing terrorist activities,” he added, noting that the Biden administration had previously “sanctioned hundreds of targets involved in Iran’s illicit oil and petrochemical-related activity.”

The latest U.S. effort to punish Iran and cut off funding for the terrorist groups it backs comes after months of stepped up activity by Hezbollah in Lebanon, which has been striking Israel’s northern border, and by the Houthis in Yemen, who have been attacking commercial ships in the Red Sea. Both Hezbollah and the Houthis have said they are fighting in allegiance with Hamas after it led an attack on Israel on Oct. 7 and set off the war in Gaza.

Tensions between Israel and Iran have also flared in recent months. In April, Iran launched a drone and missile attack on Israel after an Israeli strike killed several senior Iranian commanders at Iran’s embassy complex in Syria.

The move to cut off funding to Iran and its proxies targeted more than two dozen companies based in Hong Kong, the United Arab Emirates and the Marshall Islands that the Treasury Department said had ties to Iranian or Turkish currency exchanges and businesses that helped Iran’s military groups mask revenue generated abroad. Those funds are used to buy and develop advanced weapons, like aerial drones, and to supply Iran’s proxies, U.S. officials said.

Concerns about Iran’s role in supporting Middle Eastern militant groups were also emphasized at a series of meetings in Washington this week between senior administration officials and Yoav Gallant, Israel’s defense minister.