This file photo shows Lee Jin-woo, former head of the Capital Defense Command. (Yonhap)
This file photo shows Lee Jin-woo, former head of the Capital Defense Command. (Yonhap)

Two former military commanders and a former spy agency official are set to testify as witnesses during President Yoon Suk Yeol's impeachment trial Tuesday.

Lee Jin-woo, former head of the Capital Defense Command; Yeo In-hyung, former head of the Defense Counterintelligence Command; and Hong Jang-won, former first deputy director of the National Intelligence Service, have been called to testify at the trial's fifth formal hearing at the Constitutional Court at 2 p.m.

The three were called as witnesses by the National Assembly's legal team, which is acting as the prosecutor in the case on whether to uphold or reject the Assembly's impeachment of Yoon over his short-lived Dec. 3 imposition of martial law.

The National Assembly's team is expected to question the witnesses first before Yoon's legal defense team asks questions to verify their claims.

The court's justices will then question the witnesses as well.

While under arrest, Lee and Yeo have been indicted on charges of playing a key role in an insurrection.

Lee reportedly told prosecutors Yoon ordered him on the day that martial law was imposed to instruct troops to carry out lawmakers from inside the National Assembly building, "firing guns and breaking down doors" if necessary.

Yeo allegedly received orders from then Defense Minister Kim Yong-hyun to arrest and detain opposition leader Lee Jae-myung and then ruling party leader Han Dong-hoon, among others.

Hong, meanwhile, has told lawmakers he received a phone call from Yoon instructing him to "round them up and get rid of them."

Yoon has defended his actions as a "warning" to the opposition party while denying giving orders to arrest politicians. (Yonhap)