The letter, sent on Wednesday to the Treasury Department and its top official, Janet Yellen, singled out several entities that the Israeli government designated in 2021 as proxies for the Popular Front for the Liberation of Palestine terrorist group. It comes one week after the Treasury Department’s designation of the Samidoun Palestinian Prisoner Solidarity Network, one of those Israeli-designated terrorist groups, as an “international fundraiser” for the PFLP.

“It is now time for the Remaining PFLP terror proxies as well as any Boycott, Divestment and Sanctions affiliate that operates in a similar manner to also be designated by the Office of Foreign Assets Control as Specially Designated Nationals,” the watchdogs said in the letter, which was led by a think tank called Zachor Legal Institute and over a dozen groups aiming to fight antisemitism.

“The Samidoun Designation was only the tip of the terror support iceberg and without further action to disrupt support to designated foreign terror organizations it is guaranteed that the activities once conducted by Samidoun will end up being shifted over to the Remaining PFLP terror proxies as well as other elements of BDS,” the groups continued in the letter.

News of the further pressure comes on the heels of pro-Israel groups celebrating the Biden-Harris administration’s sanctioning of Samidoun, which was at the center of a Washington Examiner investigation over the last two years into terrorism ties in the United States. Samidoun has long been housed at a nonprofit group in Arizona called Alliance for Global Justice, which was booted from payment processing platforms such as PayPal due to reporting from the Washington Examiner.

Samidoun, the Treasury Department said in a press release in October, claims to provide humanitarian support overseas but is, in actuality, funding terrorists. Samidoun is notably behind protests across the world, including in the U.S., in favor of Hamas after the terrorist group’s Oct 7. attack last year on Israel that killed over 1,200 people.

In its Wednesday letter, the pro-Israel watchdogs zeroed in on their thinking for the need for sanctions on the Union of Palestinian Women’s Committees, Addameer, the Bisan Center for Research and Development, Al-Haq, Defense for Children International, and the Union of Agricultural Work Committees.

These foreign entities, the watchdogs told the Biden-Harris administration, “provide material support for the PFLP and likely other terror organizations such as Hamas and Hezbollah.”

Al-Haq, the Washington Examiner reported in 2023, is funded by Democratic megadonor George Soros, and its leader, Shawan Jabarin, has faced convictions and prison time for arranging events for the PFLP. The Union of Agricultural Work Committees was notably booted off online fundraising platforms after reporting from the Washington Examiner laid bare its ties to the PFLP.

Signatories of the Wednesday letter included the Orthodox Jewish Chamber of Commerce, StopAntisemitism, the American Association of Jewish Lawyers and Jurists, and other organizations aiming to fight antisemitism.

“Since the Oct. 7, 2023, Hamas terror attack on Israel, BDS aligned groups have swarmed the United States in support of Hamas, Hezbollah, and the PFLP,” their letter read. “These groups operate with funding and logistical support from forces seeking to destabilize the United States and turn American streets and campuses into the next terror front.”

The Washington Examiner reached out to the Treasury Department for comment.