Presidents Biden and Yoon pledged to deepen and broaden the scope of the U.S.-South Korea alliance, but their success could depend on how China, Japan, and North Korea respond.

The United States and South Korea should pursue an expanded nuclear agreement that supports the production of civilian nuclear power and enhances extended deterrence against the North Korean threat. …

The coronavirus pandemic has reduced global carbon emissions, but that progress won’t last unless governments act to reduce emissions permanently and prepare for future disasters.

As COVID-19 continues to ravage countries including Brazil and India, scientists warn that cases and deaths are being undercounted. Without accurate tallies, government responses won’t be enough to d…