And as the presidenteighs his military options tonight his defense secretary, James Mattis, arriving at the white housr that national security count meeting today. Tonight, a. Destroyer already in the mediterranean. There is British aircraft in the region, and a French warship just off the coast of N. ABC's chief global affairs correct Martha Raddatz tonight on what could be coming. Reporter: T, the U.S. Resolved to make Syria pay a price. Defense secretary Mattis is convinced those images show a chemical attack. The use oem weapons and some things are simply inexble, beyond the pale, and test interest of not just the chemical weapons convention, but of civilization its Reporter: The presi is we hions to strike ligh gheavy.warships and planes from the U.S., France and Britain are in place Eady to go, whenever the order is given. It wirobably be a S, quick, hard put the Assad regime and that could T. It all depends on how the Russians react and how the Syrians react in response. Reporter: Secretary Mattis knows complicated and dangerous a military response can be. We're trying to stop the murder of in people. On a strategic level, it's how do we keep this fr escalating out of cont if you get my drift on that. Reporter:t year's ha missile strike on a Syrian airfield did not seem to dissuade Assad from using chemical weapons again and those Syrian planes were back in the within days. But gotoo far, in a response, could inflame the on. Ssian newsper is reporting that the Russians are in secret talks with the U.S., asking fo targeting information to get their personnel and aircraft out of the way. So, let's bring back in Martha Raddatz, again live with us from waon. And Martha, it was Monday that presidump announced to the world that H would have a decision wit 24 to 48 hours. That timrame has clearly passed now. We've now watched the president and his teanging in allies on this, who were also outraged at what they saw. Reporter:y were,david. But I think C helds slowed this down. These are big decisions, to target andwhen. Also, because trump isn going this alone, inste workingith those allies, there is muc coordination. David? Martha Raddatz with us every step of the way on this.