The Taliban surged back to power two decades after U.S.-led forces toppled their regime in what led to the United States’ longest war.

Negotiations between the United States and North Korea have proceeded in fits and starts for decades. But they have failed to halt the advance of North Korea’s nuclear and missile programs.

The United States and China have one of the world’s most important and complex bilateral relationships. Since 1949, the countries have experienced periods of both tension and cooperation over issues …

Since India’s independence, ties with the United States have weathered Cold War–era distrust and estrangement over India’s nuclear program. Relations have warmed in recent years and cooperation has strengthened across a range of economic and political areas.