In a rare visit, the first in four years, North Korean leader Kim Jong-il has entered Chinese territory, according to South Korean officials. A South Korean government official told the South Korean news agency Yonhap, "We have confirmed the arrival of a special train at [the Chinese border city] Dandong, and we believe it is highly likely that Chairman Kim is on board." The visit comes at a tense moment for North and South Korean relations: South Korea may be planning a response to a suspected North Korean attack on a South Korean naval ship, in which South Korea lost 46 sailors. China may be able to ease tensions and act as a mediator to stabilize the region. The North Korean leader's visit may also concern his nation's economic vulnerability—China is North Korea's largest financial supporter, and analysts say that Kim may be crossing borders to seek monetary aid. The visit is Kim's first overseas trip since his suspected stroke in 2008.