evidence: U.N. Command — a multinational military body tasked with enforcing the armistice between South and North Korea — said it is investigating Seoul’s claims that around 20 North Korean troops crossed the Military Demarcation Line at 12:30 p.m. Sunday, according to an unattributed email statement from the command. The demarcation line marks the border between the two Koreas within the DMZ, a buffer zone roughly 150 miles long and 2½ miles wide. [...] The DMZ contains thick foliage that makes it difficult to see signs denoting one’s territory, South Korean Army Col. Lee Sung-jun said during a news conference Tuesday.