Iran is preparing a counter-proposal after rejecting the U.S. nuclear deal, prompting President Trump to caution that "time is running out."

Even as the United States and Iran grapple with each other’s nuclear red lines, the simple fact of engagement underscores a pragmatic turn for Tehran regarding President Donald Trump.

An outline by the Trump administration would allow Iran to continue enriching uranium at low levels while a broader arrangement is worked out that would block the country’s path to a nuclear weapon.