Xuanyu Harry Pang, 38, entered the guilty plea in early November and it was unsealed in a federal district court in Chicago on Thursday, the department said in a statement.

According to court documents, Pang communicated with an individual in Colombia in 2021 about assisting with an attack "involving Iranian actors" to avenge the death of Iranian general Qassem Soleimani, who was killed in 2020 in a US drone strike.

A covert FBI employee, posing as an affiliate of Iran's Quds Force, subsequently communicated online with the individual in Colombia, who put them in touch with Pang, who was stationed at Naval Station Great Lakes in North Chicago, they said.

Pang later met several times with covert FBI employees to discuss planning for an attack on Naval Station Great Lakes.

"Pang displayed photos and videos on his phone of multiple locations inside the Naval Station," according to court documents.

"He also provided two US military uniforms -- for operatives to wear inside the base during the attack -- and a cell phone that could be used as a test for a detonator."

Pang pleaded guilty to conspiring to destroy national defense material and other charges.

He faces a maximum of 20 years in prison.

The United States has accused Iran of seeking to assassinate a number of high-ranking US officials to avenge Soleimani's death, including President Donald Trump.