On the eve of the G20 summit in Seoul, Simon Johnson, professor at the Sloan School of Management, Massachusetts Institute of Technology and the former chief for the International Monetary Fund, explains the issue.
North Korea followed through on its threats and conducted its third nuclear test on Tuesday, Monday night in the United States, believed to be its most powerful to date. The test was roundly criticized, even by North Korea's lone ally, China. A United Nations Security Council meeting has been called.
People who've arrived here from other countries are often able to see the United States in simpler terms, and in ways that reflect, and contrast with, their own backgrounds. The World's Alex Gallafent reports from Alphabet City, New York.
North and South Korea exchanged artillery fire today in one of the most dramatic confrontations between the two since the Korean War ended without a peace treaty. Reporter Jason Strother has reaction from South Korea.