The Trump administration could designate an element of Iran's military as a foreign terrorist organization as soon as Monday in an unusual move, according to multiple reports.

Though the State Department has long labeled Iran the world’s leading state sponsor of terrorism, it has never before classified a branch of a foreign government’s military as a terrorist group.

The Islamic Revolutionary Guard Corps is a powerful branch of Iran’s Armed Forces and, along with its Quds Force, supports terrorists elsewhere in the world, guides Iran's global proxies, carries out cyberattacks and assassinations, funds missile development, and wields huge influence both inside the country and around the region.

The Treasury Department took a step in this direction in 2017, when it labeled the Revolutionary Guard as a Specially Designated Global Terrorist, which made it easier for the U.S. to combat Iran's terrorism funding by targeting its financing.

Secretary of State Mike Pompeo has reportedly wanted to label the Revolutionary Guard a terrorist group since he accepted the job.

A GOP aide told the Washington Examiner that Sen. Ted Cruz, R-Texas, "is well-known to be planning an even broader set of sanctions against the Islamic Revolutionary Guard Corps for this Congress that will build on his last effort, in which redundant sanctions for their activities would be layered on."

Cruz has been a prominent voice pushing for the Revolutionary Guard to be designated a terrorist group, introducing bills during both the Obama and Trump administrations. Cruz first introduced the IRGC Designation Act in 2015, saying that “for more than three decades, Iran’s IRGC has been a leading proponent of radical Islamic terrorism around the globe.” He introduced it again in 2017, saying: “It is time to call this enemy by name and speak with clarity and moral authority.”

The impending decision to designate the Revolutionary Guard as a terrorist organization comes after a surprise announcement from the State Department's Brian Hook last week, who revealed that Iran is responsible for the deaths of more than 600 American service members in Iraq, higher than the previous estimate of 500.

A spokesman for the Defense Department told the Washington Examiner the exact figure is 603.

Commander Sean Robertson said the casualties were from improvised explosive devices, rockets, mortars, rocket-propelled grenades, and small-arms and sniper attacks by Iranian-backed militants.

The Defense Department would not reveal the names of the 603 U.S. service members.

Cruz had also pushed the Pentagon for answers on this issue. A spokesperson for Cruz told the Washington Examiner: “Sen. Cruz has been fighting for years to get Americans as much information as possible about the hundreds and hundreds of Americans killed by Iran in Iraq. The Obama administration downplayed the scope and nature of these murders in the interest of promoting its diplomacy with Iran, including the Obama nuclear deal.”

The Obama administration entered into the Iran deal in 2015, to much criticism from Republicans. Following the U.S.’s withdrawal from the deal in 2018, Pompeo explained the Trump administration’s reasoning by labeling Iran an “outlaw regime" that couldn't be trusted and saying that "the Iranian regime will do whatever it takes to maintain its grip on power and spread its revolutionary ideology."

Pompeo emphasized that “the Islamic Republic of Iran is not a normal state" because "normal states do not support terrorism within their armed forces" like Iran does with the Revolutionary Guard.

The Cruz spokesperson said other questions about Iran remained unanswered.

“It’s important for the Trump administration to continue making public all of the ways that our foreign policy was subordinated to the Iran deal, including secret side deals which have never been made public," Cruz's spokesperson said. "The administration must also immediately cut off the resources the ayatollahs are using to attack us."

Sen. Tom Cotton, R-Ark., who also called for answers on Iran’s involvement in the killing of American soldiers, told the Washington Examiner: “Anyone who served in Iraq knows that Iran has the blood of hundreds of American soldiers on its hands. I commend Secretary Pompeo for releasing this information to the American people. The ayatollahs’ outlaw regime must continue to face consequences for the murder of American troops.”