Seoul —

Secret drone flights from South Korea to the heart of Pyongyang were part of a ploy by the former president to rattle the North Korean leader, South Korean prosecutors have alleged as they released new details of plot they say preceded a foiled attempt to declare martial law.

Memos found on a senior defense official’s phone purportedly reveal plans by former president Yoon Suk Yeol and two other senior defense officials to aggravate Kim Jong Un enough to justify a shocking late-night military control order issued last December.

Prosecutors released the evidence on Monday, appearing to confirm North Korea’s claims that South Korea sent covert drones to the country to drop anti-regime leaflets last October. The flights prompted a rare and fiery statement from Kim Yo Jong, Kim’s powerful sister.

The North vowed to sever all road and rail connections to the South, blowing up two roads within its territory, but stopping short of military action. Weeks later, Yoon declared martial law, citing the need to protect the liberal South from “North Korean communist forces.”

The snap decree was lifted within hours when South Korean lawmakers pushed past troops to vote it down, the first step in a reckoning for Yoon that’s still playing out in court.

A new indictment Monday adds to Yoon’s mounting legal battles, which include a trial underway for alleged insurrection, and provides more pieces to a political puzzle that’s yet to be fully explained.

Yoon denies he ordered drones to fly to Pyongyang to provoke North Korea and that he attempted to stage an insurrection through martial law.

Yoo Jeong-hwa, one of Yoon’s lawyer