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A 15 SECOND PHOTO-OP SAID IT ALL. POLITE, BUSINESSLIKE BUT NO MORE, FOR LEADERS WHO COULDN'T BE FURTHER APART.

IN AN ORNATE ROMANOV PALACE, VLADIMIR PUTIN WELCOMED PRESIDENT OBAMA AND OTHER G-20 LEADERS TO AN ECONOMIC SUMMIT OVERTAKEN BY SYRIA.

OBAMA'S USING SIDE-MEETINGS HERE TO RALLY SUPPORT FOR A MILITARY STRIKE ON BASHAR ASSAD'S REGIME THAT THE RUSSIANS STAUNCHLY OPPOSE.

SOUNDBITE: President Barack Obama

"The use of chemical weapons in Syria is not only a tragedy but also a violation of international law that must be addressed."

(SOT: Mark Smith Standup)

Of course Syria's NOT their only bone of contention with Putin. There's the asylum given NSA leaker Edward Snowden. And disputes over missile defense and human rights. Coming in here, the president said relations have "hit a wall."

Many G20 leaders are dubious of a Syria strike NOT blessed by the U.N. Of the allies, only France looks ready to take part.

The summit skepticism mirrors that in Congress, where Obama's aides have been getting pointed questions.

SOUNDBITE: Senator Susan Collins, R-Maine.

"What if we execute the strike and then he decides to use chemical weapons again? Do we strike again? Well, that's the definition of further entanglement."

BEFORE CONGRESS VOTES, OBAMA'S HOPING TO MAKE BELIEVERS OF THE DOUBTERS. BUT BOTH AT HOME AND AT THIS GLOBAL SUMMIT, HE FACES A STEEPLY UPHILL FIGHT.

MARK SMITH, ASSOCIATED PRESS, AT THE G-8 SUMMIT, ST. PETERSBURG

SHOTLIST:

POOL - AP CLIENTS ONLY

St. Petersburg, Russia - Aug. 5, 2013

1. Shots of Obama and Vladimir Putin shaking hands

2. Wide shot of the hall where the G20 is taking place

3. Wide shot inside the hall of the G20 meeting

4. Mid shot of Obama listening

5. Mid shot of German Chancellor Angela Merkel and British Prime Minister David Cameron listening

6. Obama's bilateral meeting with Japanese Prime Minister Shinzo Abe

AP Television FILE - AP Clients Only

Syria - Exact date, location unknown

7. Close shot of smoke following an explosion

8. Mid shot of Syrian President Bashar Assad

POOL - AP CLIENTS ONLY

St. Petersburg, Russia - Aug. 5, 2013

9. SOUNDBITE: (English) Barack Obama, US President

"The use of chemical weapons in Syria is not only a tragedy but also a violation of international law that must be addressed."

POOL - AP CLIENTS ONLY

St. Petersburg, Russia - Aug. 5, 2013

10. Shots of G20 meeting

11. Close shot of French President Francois Hollande

12. Mid shot of Putin at summit

POOL - AP Clients Only

Washington, DC - Aug. 4, 2013

13. Mid shot of Secretaries John Kerry and Chuck Hagel testifying before House Foreign Relations Committee

14.

15. John Kerry pointedly responding to committee

POOL - AP Clients Only

Washington, DC - Aug. 5. 2013

16. SOUNDBITE: (English) Senator Susan Collins, (R) Maine

"What if we execute the strike and then he decides to use chemical weapons again? Do we strike again? Well, that's the definition of further entanglement."

POOL - AP CLIENTS ONLY

St. Petersburg, Russia - Aug. 5, 2013

17. Mid shot of Obama bilateral meeting with Abe

18. Obama walking with other leaders towards the summit