Understanding nuclear arms control

The New Strategic Arms Reduction Treaty was signed 16 years ago in April between the U.S. and Russia. It expired this February, with no sign of extension after Washington failed to respond to Russia's proposal to uphold the treaty informally while maintaining its core nuclear limits. Meanwhile, the broader Non-Proliferation Treaty faces potential strain as Iran considers withdrawing amid Israeli and U.S. actions. What do these developments indicate about fundamental shifts in global security? Is there hope as world leaders gather in New York later this month for the NPT Review Conference?