U.S. President Barack Obama plans to visit South Korea in April for talks with President Park Geun-hye about the alliance between the two countries, North Korea's nuclear program and other issues, the White House said Wednesday. The visit is part of a four-nation trip that also includes stops in Japan, Malaysia and the Philippines, the White House said in a statement. With the full itinerary yet to be announced, he is expected to stay in South Korea for two days from April 23 following his trip to Japan, according to diplomatic sources in Washington.