Iran nuclear talks: Is US following path that failed with North Korea?

In the months since talks aimed at reviving the Iran nuclear deal restarted, Tehran has announced crossing one technical milestone after another in its nuclear program and has continued racing toward ... what exactly?

The answer to that question remains unclear. But for some nuclear proliferation experts, Tehran may at least be weighing the eventual need for a regime-change insurance policy that brings it to the brink of having a nuclear weapon.

Iran insists, as it has for years, that its nuclear program is intended solely for peaceful purposes. And...