Rhee Keun, a Korean YouTuber and former Korean Navy special forces officer, on Monday (Yonhap)

Rhee Keun, a Korean YouTuber and former Korean Navy special forces officer who went to Ukraine a year ago to help the country's defense against Russia, on Monday admitted to charges of violating passport law.

Rhee was indicted in January on charges of traveling to the war-stricken country in defiance of a travel ban. In March last year, Rhee entered the European country to help the Ukrainian forces, which he publicized on social media.

He voluntarily turned himself in to police after he returned to Korea in May, citing injuries.

South Korea has banned its nationals from traveling to all regions of Ukraine since February 2022 amid safety concerns. Under the law, those who enter the country without approval can face up to a year in prison or a maximum fine of 10 million won ($7,650).

Pleading guilty at the Seoul Central District Court, Rhee said, "I did not participate in the Russia-Ukraine war for Ukraine, but for the innocent people. I apologize for violating the passport law, but still think it was a good decision to participate in the war."

Meanwhile, Rhee allegedly hit a YouTuber in the court hallway right after the hearing. The YouTuber followed Rhee around and repeatedly asked questions regarding another person to whom Rhee is indebted, according to reports.