The US government is “intensely tracking” an ongoing threat by Iran against current and former US officials, Secretary of State Antony Blinken said Wednesday.

“This is something we’ve been tracking very intensely for a long time, an ongoing threat by Iran against a number of senior officials, including former government officials like (former President Donald Trump) and some people who are currently serving in the administration,” the top US diplomat said in an interview with NBC’s “Today” show.

“It’s something we take very, very seriously. We’re looking at it very carefully,” Blinken said.

Law enforcement officials have been concerned about the persistent threat of Iran potentially attempting to assassinate former Trump officials and the former president himself, multiple sources familiar with the matter have previously told CNN. There also has been a noticeable surge of online messaging from Iranian accounts and state-backed media mentioning Trump, which has raised security concerns among US officials.

US officials have not detailed the threats against current officials, and Blinken on Wednesday did not reveal further information.

Trump was briefed on Tuesday by the Office of the Director of National Intelligence about “real and specific threats from Iran to assassinate him in an effort to destabilize and sow chaos in the United States,” his campaign said. A spokesperson for ODNI acknowledged the briefing but declined to address any specifics.

“Big threats on my life by Iran. The entire U.S. Military is watching and waiting. Moves were already made by Iran that didn’t work out, but they will try again,” Trump said in a post on Truth Social early Wednesday morning.

Iran has repeatedly vowed revenge for the US military’s killing of Qasem Soleimani, the commander of the Iranian military’s Islamic Revolutionary Guard Corps, who was killed by a US airstrike at Baghdad International Airport in January 2020. And former senior Trump administration officials who worked on national security have had tight security since leaving the government.

In his social media post on Wednesday, Trump also thanked Congress after the Senate unanimously passed a bill Tuesday guaranteeing that Trump and Vice President Kamala Harris receive the same level of Secret Service protection as a sitting president. The bill directs the Secret Service director to apply uniform standards for protection of presidents, vice presidents and major presidential and vice presidential candidates.

Congress is considering additional money for the Secret Service as part of its effort to keep the government funded ahead of a September 30 deadline. An additional $231 million for the Secret Service is included in a continuing resolution the House could vote on as soon as Wednesday.

CNN’s Evan Perez, Zachary Cohen, Natasha Bertrand, Kylie Atwood and Kristen Holmes contributed to this report.