By MICHAEL FALCONE ( @michaelpfalcone )

NOTABLES

• CONFIRMED - VIDEO OF SOTLOFF EXECUTION IS AUTHENTIC: A newly released video showing the Islamist terror group ISIS' execution of U.S. journalist Steven Sotloff has been deemed authentic, President Obama confirmed earlier today at a joint news conference in Estonia. "Overnight, our government confirmed that, tragically, Steven was taken from us in a horrific act of violence," Obama said. The president expressed sadness for Sotloff's relatives, and said the barbaric acts "stiffen our resolve," adding: "Those who make the mistake of harming Americans will learn that we will not forget and that our reach is long and that justice will be served." http://abcn.ws/1qaSTTN

• OBAMA SUGGESTS ISIS MUST BE DESTROYED (OR MAYBE NOT): President Obama offered a mixed message today about what exactly the United States wants to do about ISIS, according to ABC's JONATHAN KARL. At first, the president offered what seemed to be an unambiguous goal. "The bottom line is this: Our objective is clear and that is to degrade and destroy ISIL so it is no longer a threat," he said. But when ABC News Radio White House correspondent ANN COMPTON asked the president to clarify whether the United States now wants ISIS destroyed, the president seemed to significantly backtrack. "Our objective is to make sure they aren't an ongoing threat to the region," he said. Then, in response to another question, he seemed to backtrack even further: "We know that if we are joined by the international community, we can continue to shrink ISIL's sphere of influence, its effectiveness, its military capability to the point where it is a manageable problem." http://abcn.ws/1qaYv04

• BOTTOM LINE: Making ISIS a "manageable problem" sounds like a far cry from destroying it.

THE ROUNDTABLE

ABC's RICK KLEIN: What we've got here is a failure to communicate. A string of imprecise phrases and comments have complicated President Obama's already difficult task of expressing to the American people how going to war against a terrorist army in Iraq and Syria isn't the same as going to war in Iraq and Syria. Last week the president said, but didn't entirely mean, "we don't have a strategy" to defeat ISIS in Syria. Then he told a crowd at a fundraiser the "messy" world is something we're "just noticing now in part because of social media." And this morning in Estonia, the president went from a goal of "degrade and destroy ISIL" to "shrink ISIL's sphere of influence … to the point where it is a manageable problem." It's times like these that the president might be better positioned if he were known for his gaffes. Instead, the imprecision is fueling domestic criticism of a president who isn't quite acknowledging the depth of the challenges at hand.

ABC's JEFF ZELENY: President Obama isn't backing away from his pledge to take executive action on immigration - not explicitly, at least - but his end-of-the-summer deadline is out the window. That's the latest word from the White House, with press secretary Josh Earnest saying yesterday: "There is the chance it could be before the end of the summer, there is the chance it could be after the summer, but the fact is that the president will act." Here is the bottom line: The Rose Garden promise of executive action is playing poorly for Democrats in red-state Senate contests, so this is one thing the White House can try to do in its quest to hold the Senate. ABC News surveyed Democrats in a dozen key races, only one gave a thumbs up to the president acting alone. Sen. Mark Pryor of Arkansas was among the sharpest critics, voicing his disapproval like this: "I, too, am frustrated with the partisanship in Washington, but that doesn't give the president carte blanche authority to sidestep Congress when he doesn't get his way." So that explains why the president is likely to wait until after November to act.

ABC's SHUSHANNAH WALSHE: Attack ads are nasty and they can make an impact, they sway voters and that's why candidates use them. Even though they always complain about them and fein shock and suprise about just how dirty the opposing campaign has gotten. But, every now and then a candidate runs an ad that actually is shocking. So surprising that the ad and the candidate that runs it becomes the story. That's exactly what has happened in Alaska. The race that could give control to Republicans or if Sen. Mark Begich is victorious possibly hold it for Democrats. Begich ran an ad over the holiday weekend essentially blaming his Republican opponent Dan Sullivan for being soft on crime, so soft that one of the worst crimes in Alaskan history was able to take place. That's not true and now the ad and how much the victims' family wanted it down has become the story, not the actual claim. It can be a fine line between what crosses the line and ad attack ads are the norm, but maybe we can agree dragging up other families' pain should be out of bounds.

HAPPENING TONIGHT

WATCH LIVE: NORTH CAROLINA SENATE DEBATE. ABCNews.com will be livestreaming the kick-off North Carolina Senate debate between Democratic Sen. Kay Hagan and her GOP challenger, State House Speaker Thom Tillis. This is the first of three debates between the two contenders between now and Election Day. ABC's GEORGE STEPHANOPOULOS will moderate a subsequent debate on Oct. 7. Today's face-off, hosted by the North Carolina Association of Broadcasters Educational Foundation, begins at 7 P.M. Eastern. http://abcnews.go.com/live

BUZZ

with ABC's ERIN DOOLEY

350 MORE U.S. TROOPS TO IRAQ, WHITE HOUSE ANNOUNCES. An additional 350 U.S. troops will go to Iraq to protect U.S. personnel stationed in Baghdad, the White House announced Tuesday, ABC's CHRIS GOOD and LUIS MARTINEZ report. The State Dept. had requested extra military personnel for security, and after the Department of Defense reviewed that request and recommended it be granted, President Obama approved the additional forces today, White House Press Secretary Josh Earnest announced in a statement to reporters. http://abcn.ws/1rimZV7

AD CONTROVERSY ROILS ALASKA SENATE RACE. The Alaska Senate race, a campaign that could be the tightest in the country, is getting very nasty, ABC's SHUSHANNAH WALSHE notes. The campaign of Sen. Mark Begich, D-Alaska, is coming under fire for running a political ad referencing a horrific Anchorage crime and continuing to run the commercial even after the victim's family asked the campaign to stop. http://abcn.ws/1A2Fiib

ERIC CANTOR'S DEFEAT PAYS OFF WITH $1.4M WALL ST. SIGNING BONUS. Former House Majority Leader Eric Cantor is riding his unexpected primary defeat straight to the bank, ABC's BENJAMIN SIEGEL notes. The seven-term Virginia Republican has joined New York investment bank Moelis & Company and will receive a $1.4 million signing bonus. He will get the titles of vice chairman and managing director, the company announced Tuesday. Cantor, who will also join the company's board, will make at least $3.5 million over two years with Moelis- nearly equivalent to 20 years' work as House majority leader, which pays $193,000 annually. http://abcn.ws/1w31LeE

U.S. AIRSTRIKE IN SOMALIA TARGETED AL SHABAAB'S TOP LEADER. A United States military airstrike in Somalia on Monday targeted Ahmed Abdi Godane, the head of the militant group al Shabaab, the Pentagon confirmedTuesday, according to ABC's LUIS MARTINEZ and DANA HUGHES. An assessment to determine if Godane was killed in the airstrike is ongoing. If confirmed Godane's death would be a significant jolt to the Somali militant group affiliated with al Qaeda that took credit for last year's deadly attack at a Kenyan mall that killed at least 67 civilians. http://abcn.ws/1sXWNgV

IN CASE YOU MISSED IT

REPORTER'S NOTEBOOK: CATCHING THE LAST FLIGHT ON AIR FORCE ONE. The proud aircraft known 'round the globe as Air Force One never ceases to impress. Especially on this brilliantly sunny day as I board for the last time. President Obama is heading to a summit in Europe one week before I retire, ABC's ANN COMPTON notes. As White House correspondent across seven presidencies and an amazing arc of history I feel more nostalgic about a final ride on Air Force One than any other perk that the White House press enjoys. Its cabins and crew are as comfortable as home to me. http://abcn.ws/1w3COj0

WHO'S TWEETING?

@pfeiffer44: Historic moment here as @AnnCompton asks President Obama a question on her final trip. The q was tough smart and fair just as you wld expect

@PeterNicholas3: Fundraisers say Maryland Gov. Martin O'Malley is inching toward a Democratic presidential run http://on.wsj.com/1uw76d9

@TCurry_Himself: Roll Call's list of the 10 most vulnerable House members includes Republicans Lee Terry & Mike Coffman. http://atr.rollcall.com/house-races-2014-most-vulnerable-members-september/ … via @rollcall

@PhilipRucker: Michelle Nunn is trying to revive & inherit her dad's centrist image. A very nice @ColbyItkowitz dispatch from GA http://www.washingtonpost.com/politics/former-sen-sam-nunn-tells-georgia-voters-michelle-nunn-would-be-his-ideological-heir/2014/09/02/4e38725c-2f77-11e4-994d-202962a9150c_story.html …

@mkraju: Main reason voters think U.S. is headed in wrong direction is a "lack of leadership," rather than spending/ACA https://mediarelations.gwu.edu/sites/mediarelations.gwu.edu/files/GW%20BG%2055%20questionnaire.pdf …