Kerry meets Putin in Moscow on Syria mission

US Secretary of State John Kerry met with Russian President Vladimir Putin in Moscow Tuesday, seeking common ground on issues including the conflict in Syrian.

"The United States believes that we share some very significant common interests with respect to Syria — stability in the region, not having extremists creating problems throughout the region and elsewhere," Kerry said, according to Reuters.

Washington and the Kremlin — Syrian President Bashar al-Assad's most powerful ally — both endorsed a diplomatic solution last year. Where they differ is on how to handle Assad's fate, with Moscow saying his exit from power cannot be a precondition for talks.

"We have their formal commitment with their agreement to the Geneva Communique of June 30, 2012, but now we need to go beyond formal commitments like that to figure out if there are ways to actually build off of it," an unnamed US official told Reuters.

Since the agreement last summer, the Syrian crisis has steadily worsened, with more than 70,000 people dead, millions displaced, and recent unconfirmed reports claiming that chemical weapons have been used.

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It's unclear who could have used the suspected chemical weapons, but according to a senior State Department official, "we have no information to suggest that [rebel groups] have either the capability or the intent to deploy or use such weapons."

The United Nations has been unable to confirm or dismiss reports of nerve gas such as sarin, as Assad's government has so far refused an investigative team access to areas where it would need to collect soil, blood and tissue samples.

Both Israel and the United States characterized chemical arms use in Syria as a "game-changer" that could instigate international military intervention. Last week US Defense Secretary Chuck Hagel said the United States might consider supplying the rebel opposition with lethal arms. "Arming the rebels — that's an option," he said.

The State Department noted that Kerry's visit will focus on "the entire bilateral relationship" with Russia, "not just on Syria," though two recent air raids (thought to be Israeli) into Syria over the weekend will likely be discussed.

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Another issue, following the Boston Marathon attack that killed three people and wounded 264, will be counterterrorism cooperation. The two bombing suspects, Tamerlan and Dzhokhar Tsarnaev, are ethnic Chechens who lived in the US.

The US is "looking for new ways of cooperating, both with regard to the current investigation, but also looking forward to ways that we can deal with what we consider to be a common set of interests that we have with Russia on that front," a senior State Department official said.