Tensions with Iran are running hot, and the standoff comes down to one demand — Iran does not get a nuclear weapon.

• Trump's single red line with Iran is no nuclear weapons, with everything else negotiable.
• Iran's foreign minister has said the country is ready for "all options," including doomsday scenarios.
• That kind of talk is being used as the argument for why Iran can never be allowed nuclear arms.
• Ordinary Americans are focused on their own finances, not the crisis abroad.

Outlook: Expect continued pressure and hard talk on both sides, with the nuclear question the one issue that could trigger escalation.