The president's confrontation with a Code Pink heckler in his speech today at National Defense University was quite a moment.

But don't lose sight of the big picture - the heckler was a side show. This was one of President Obama's most significant speeches, an attempt to mark a shift in what is known as (but he does not call) the war on terror.

First, on the heckler:

The heckler hammered Obama over drone strikes and failing to shut down Guantanamo. She was able to go on and on and on. At first the president seemed rattled, telling her, "Why don't you sit down and I'll tell you exactly what I'm going to do…. You should let me finish my sentence."

She quieted down, but only temporarily.

Moments later she started yelling again from the back of the room. "Now, this is part of free speech, is you being able to speak, but also you listening and me being able to speak. All right?" Obama said to applause.

But as the heckling continued, the president incorporated her dissent into his speech.

"I'm willing to cut the young lady who interrupted me some slack because it's worth being passionate about," he said, adding, "The voice of that woman is worth paying attention to. Obviously - obviously I do not agree with much of what she said, and obviously she wasn't listening to me in much of what I said. But these are tough issues, and the suggestion that we can gloss over them is wrong."

ABC News' Luis Martinez reports that the heckler, long-time Code Pink protestor Medea Benjamin, was there as a member of the press. Code Pink is an anti-war organization, and Benjamin represented herself as working for the blog Common Dreams. According to a Defense official, the White House handled the press list.

But why was she allowed to keep interacting with the president? "Because it's America, because the president was making a speech about free speech," the official said. "Secret Service won't do anything unless it's threatening to the president. We thought she'd stop. She didn't … but when it was clear she was going to prevent the president from speaking, we asked her to leave and escorted her out."

Now, the speech:

The president who dramatically expanded the CIA secret drone war, ordered a troop surge in Afghanistan and aggressively prosecuted leakers made a forceful defense of his actions and an even more forceful case for winding down the war on terrorism.

The key line: "This war, like all wars, must end. That's what history advises. That's what our democracy demands."

On Drones:

Memo to Rand Paul: "For the record, I do not believe it would be constitutional for the government to target and kill any U.S. citizen - with a drone, or a shotgun - without due process. Nor should any president deploy armed drones over U.S. soil."

It's not clear how that squares with the four Americans who have been killed on his watch in drone strikes (apparently with absolutely no due process). But about American Anwar al-Awlaki, he said, "Of course, the targeting of any American raises constitutional issues that are not present in other strikes, which is why my administration submitted information about Awlaki to the Department of Justice months before Awlaki was killed and briefed the Congress before this strike as well."

He talked about the need to limit the use of drone strikes and pointed to a presidential order he signed yesterday saying that such strikes would not be used to punish those who have attacked America. They would only be used when a terrorist who cannot be captured poses an imminent and ongoing threat and "there must be near-certainty that no civilians will be killed or injured."

The downside of drone strikes: "Any U.S. military action in foreign lands risks creating more enemies, and impacts public opinion overseas…. The very precision of drone strikes, and the necessary secrecy involved in such actions can end up shielding our government from the public scrutiny that a troop deployment invites. It can also lead a president and his team to view drone strikes as a cure-all for terrorism."

On Guantanamo Bay

He renewed his call to close Gitmo and offered arguments based on both morality and self-interest.

Morality: "I know the politics are hard. But history will cast a harsh judgment on this aspect of our fight against terrorism and those of us who fail to end it. Imagine a future 10 years from now or 20 years from now when the United States of America is still holding people who have been charged with no crime on a piece of land that is not a part of our country. Look at the current situation, where we are force-feeding detainees who are being held on a hunger strike. I'm willing to cut the young lady who interrupted me some slack because it's worth being passionate about. Is this who we are? Is that something our founders foresaw? Is that the America we want to leave our children?"

Self interest: "During a time of budget cuts, we spend $150 million each year to imprison 166 people, almost a million dollars per prisoner. And the Department of Defense estimates that we must spend another $200 million to keep Gitmo open at a time when we are cutting investments in education and research here at home and when the Pentagon is struggling with sequester and budget cuts."

Bottom Line: "Given my administration's relentless pursuit of al-Qaida's leadership, there is no justification beyond politics for Congress to prevent us from closing a facility that it should - should have never been opened."

On Targeting Journalists in Leak Investigations

The president almost seemed to express regret for his Justice Department's relentless pursuit of leak investigations.

"I'm troubled by the possibility that leak investigations may chill the investigative journalism that holds government accountable. Journalists should not be at legal risk for doing their jobs. Our focus must be on those who break the law. That's why I have called on Congress to pass a media shield law to guard against government overreach. And I've raised these issues with the attorney general, who shares my concern."