LULU GARCIA-NAVARRO, HOST:
The killing of Iran's top nuclear scientist involved a group of highly trained assassins in what was a coordinated, brazen attack on Iranian soil. That scientist is being buried today. Iran is blaming Israel, and it says it will retaliate. But why did this happen now? And what does this mean for the incoming administration of President-elect Joe Biden? NPR's national security correspondent Greg Myre is following this story, and he joins us now. Good morning.
GREG MYRE, BYLINE: Hi, Lulu.