Ticker-US, Japan and South Korea agree to expand security ties at summit amid China, North Korea worries.

US, Japan and South Korea agree to expand security ties at summit amid China, North Korea worries. President Joe Biden and the leaders of Japan and South Korea have agreed to expand security and economic ties at a historic summit Friday at the U.S. presidential retreat of Camp David. Their meeting and their agreement come at a time that the three countries are on an increasingly tense ledge in their relations with China and North Korea.