Seoul, May 27 : A South Korean volunteer fighter in Ukraine returned home Friday after sustaining knee injuries while in action. Rhee Keun, a Navy SEAL-turned-YouTuber, arrived at Incheon International Airport at around 7.30 a.m., about three months after he left for Ukraine to fight in the ongoing war as a volunteer fighter, reports Yonhap News Agency. Addressing reporters shortly after arrival, Rhee said he had cruciate ligament ruptures on both of his knees that requires an operation. "I returned for rehabilitation and treatment... I am anxious to go back. There is a lot to do, as the war is not over yet. We should fight harder and continue to fight," he said. He briefly talked about his experiences from the war, including witnessing a Ukrainian civilian being shot and killed while he was on his first mission. "I have seen many criminal acts while witnessing the war first hand." The police however, plan to investigate him over passport law violation charges soon, as he travelled to the war-torn nation in defiance of South Korea's travel ban to Ukraine. Upon arrival, the police imposed an overseas travel ban on him. In a Twitter post a week earlier, Ukraine's International Legion of Territorial Defence said Rhee, who "sustained injuries on the battlefield... will return home for rehabilitation". South Korean nationals have been banned from travelling to Ukraine since mid-February amid safety concerns. Those who enter the country without approval can face up to a year in prison or a maximum fine of 10 million won ($7,961). /IANS