SEOUL — South Korean President Yoon Suk Yeol on Thursday angrily defended his shock decision to declare martial law last week and signaled he would not resign from office, as a second effort to impeach him gathers momentum.

       “I will fight to the end,” Yoon said in a prerecorded address Thursday, only the second time he has appeared since his ill-fated Dec. 3 attempt to impose martial law.