Good evening. It's 4.30 a.m. in Iran's capital, the middle of a sleepless night for some

as they and we wait for the next step in the crisis that escalated today with a shoot

down of an American surveillance drone. On the left is Pentagon video of it shortly

after it was hit on the right, what Iranian state TV is claiming to be video of the anti-aircraft

missile hitting its target. Now we should point out we have not independently confirmed

that. Nor is there any independent assessment of where the drone actually was, whether

it was in Iranian airspace as Tehran is claiming or not as the Pentagon says. There's new reporting

on that which we're going to bring you tonight and either way because this is in fact such a tense

moment we are taking extra care throughout the entire broadcast to clearly label any and all

unverified claims as such no matter who's making them. We're making sure to bring you strong

advocates on both sides of the debate over what to do next. The president today sent mixed

signals telling reporters he thought the shoot down was accidental but also suggesting some kind

of a response is in the works. I find it hard to believe it was intentional if you want to know

the truth. I think that it could have been somebody who was loose and stupid that did it.

You'll find out. You'll find out. You'll find out.

A short time later he briefed top lawmakers sent a majority leader Mitch McConnell saying the

president is weighing quote a measured response his words his democratic counterpart Chuck Schumer

saying he worried about the president bumbling that was his word into war with Iran. We talk about

that tonight about the risks ahead and the possibility of escalation or de-escalation. We begin

that with CNN's Barbara star at the Pentagon. So Barbara exactly what do we know happened here

because the accounts coming obviously from the US and Iran are very different. They are different

Anderson and perhaps that is not unexpected. The US began the day saying that one of its drones

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