'This Week' Transcript: Gov. Scott Walker

— -- This is a rush transcript.

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ANNOUNCER (voice-over): Starting right now on the special edition of THIS WEEK, an ABC News exclusive: for the first time ever, our cameras revealing the Persian Gulf nerve center, the heart of the U.S. campaign to take down ISIS.

Martha Raddatz with the men and women fighting America's most dangerous enemy.

Plus the GOP's man to beat, Wisconsin Governor Scott Walker is Iowa's early front-runner. Jon Karl with the exclusive interview.

And making history: the first Triple Crown winner in 37 years. Did American Pharaoh just put horse racing back on the map?

From ABC News, THIS WEEK with George Stephanopoulos begins now.

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MARTHA RADDATZ, ABC NEWS CORRESPONDENT: Good morning. I'm Martha Raddatz. We're coming to you from a Persian Gulf nation that we've been asked not to disclose, where the U.S.-led military operation against ISIS is being coordinated. Temperatures here hovering around 120 degrees.

Behind me you see one of the Predator drones or as the Air Force calls them, remotely piloted aircraft. And that's a Hellfire missile hanging below. They fly 24/7, collecting intelligence and carrying out deadly airstrikes.

I'm about to take you inside the heart of the command center of the U.S.-led campaign to defeat the jihadist group, the first time TV cameras have been allowed inside.

Just this week, an American general saying this fight will last a generation. And as we come on the air this morning, the commander in chief, President Obama, has just landed in Germany for a series of urgent meetings with allies at the G7 summit.

A major focus: his plans to stop the disturbing ISIS surge, a strategy that has come under fire.

So we begin with ABC's chief foreign correspondent, Terry Moran, at the summit with the very latest.

Good morning, Terry.

TERRY MORAN, ABC NEWS CHIEF FOREIGN CORRESPONDENT: Good morning, Martha.

President Obama's arrived in these splendid Alpine surroundings at a moment when the world is looking to him for leadership, especially in the fight against ISIS, German Chancellor Merkel welcoming the president in the small town of Krun, Mr. Obama hoisting a mid-morning beer. But the agenda here is packed, ISIS right at the top of it.

They are on the march again in Syria and Iraq. And once again Iraqi troops just running away from the battlefield in Ramadi. Defense Secretary Carter saying they showed no will to fight.

So President Obama will meet here with the Iraqi leader, Prime Minister Abadi. He wants a lot more U.S. assistance in the fight. Americans are disappointed in him. They don't see him as the leader for change and reconciliation they'd hoped.

Mr. Obama, since the beginning of his presidency, has been trying to extract the U.S. from its deep entanglements in the Middle East, but events keep dragging him back. And the leaders here, they don't think his strategy against ISIS is working and they want to see him step up his game -- Martha.

RADDATZ: Thanks, Terry.

Now inside the U.S. headquarters to take down ISIS, this joint operation space in the Persian Gulf is where the U.S. military coordinates every airstrike, all the intelligence for today and the future, comes through here. It was one year ago today that ISIS swept into Mosul in Iraq, pulling the U.S. into a war we thought had ended.

Right now we're going inside the massive operation center and going one-on-one with the general commanding the mission to defeat ISIS for good.

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