South Korea’s impeached President Yoon Suk Yeol was formally arrested early on Sunday, days after being apprehended at his presidential compound in Seoul. He faces possible imprisonment over his ill-fated declaration of martial law last month.

Yoon, who was impeached and suspended from office in December, is the first sitting South Korean president to be arrested.

Supporters of impeached President Yoon Suk Yeol stormed a Seoul court early Sunday following its decision to formally arrest Yoon.