South Korean President Yoon Suk Yeol defended his martial law decree as an act of governance and denied rebellion charges, vowing Thursday to "fight to the end" in response to attempts to impeach him and intensifying investigations into last week's dramatic move.

The main opposition Democratic Party quickly slammed Yoon's speech as "an expression of extreme delusion" and "false propaganda." Later Thursday, it and other opposition parties submitted a new impeachment motion against Yoon for a floor vote this weekend.