Obama faces showdown with Putin at G-20 summit over Syria

For Obama and Putin, handshake can't mask tension 2:52

President Barack Obama and Russian President Vladimir Putin exchanged a tense handshake Thursday to open a summit of the Group of 20 countries — a meeting meant to focus on economic issues but overshadowed by the crisis in Syria.

The meeting came a day after Putin accused Secretary of State John Kerry of lying to Congress as he presented the administration’s case for an attack to punish Syria for using chemical weapons. Obama and Putin exchanged formal greetings in front of cameras in St. Petersburg at the start of the two-day meeting.

At home, members of Congress were divided about whether to approve a resolution authorizing a U.S. strike on Syria. Senators got a closed-door briefing at the Capitol and were shown gruesome video of dozens of people apparently killed by nerve gas — a presentation that one senator described as CIA meets CSI.

“It’s horrendous,” said Sen. Dianne Feinstein, D-Calif., who said she would vote to authorize an attack.

Majority of Americans against Syrian intervention 3:18

Obama canceled a planned trip to California on Monday and will stay in Washington to work on the crisis, the White House said.

The U.S. ambassador to the United Nations, Samantha Power, said there was “no viable path forward” for support in the U.N. Security Council, where both Russia and China have veto power. Russia is a key ally of Syrian President Bashar Assad, and a Chinese official warned Thursday that a strike would send the price of oil soaring.

At the G-20, China warned that a military strike on Syria would hurt the global economy and reiterated its calls for a political solution. 

"Military action would have a negative impact on the global economy, especially on the oil price - it will cause a hike in the oil price," Vice Finance Minister Zhu Guangyao told a briefing on the sidelines of the summit.

The U.N. Secretary-General Ban Ki-moon said Thursday that its special envoy to Syria, Lakhdar Brahimi, would attend the summit in order to push for an international conference on the issue.

"A political solution is the only way to end the bloodshed in Syria," he said in a statement.

Putin has stated that U.S. plans for military strikes amounted to an act of “aggression” if they did not come with unanimous United Nations Security Council approval.

Tensions were raised further Wednesday when Putin alleged that Kerry had lied to Congress about the role of al Qaeda in the Syria conflict.

“I saw debates in Congress. A congressman asks Mr Kerry: 'Is al Qaeda there?' He says: 'No, I am telling you responsibly that it is not'," Putin said at a meeting of his human rights council in the Kremlin, according to Reuters.

"Al Qaeda units are the main military echelon, and they know this," he said, referring to the United States. "It was unpleasant and surprising for me - we talk to them, we proceed from the assumption that they are decent people. But he is lying and knows he is lying. It's sad."

Those remarks add to existing strains between Washington and Moscow over the status of NSA leaker Edward Snowden, who was granted temporary asylum by Russian authorities last month. That prompted the White House to cancel pre-planned one-on-one meetings between Obama and Putin.

There was further awkwardness for Obama when it was reported by AFP that Brazil had canceled preparations for a trip to Washington by President Dilma Rousseff. 

Rousseff, who was seated next to Obama at the summit, was said to be "furious" over last week's revelation that the NSA had been spying on her communications. 

Putin has said he would like to hold private talks with the president during the summit.

However, Obama is expected to meet instead with the leaders of France, China and Japan on the summit's sidelines in order to secure international backing for military strikes on Syria.

That action moved a step closer on Wednesday when the Senate Foreign Relations Committee voted 10-7 in favor of giving Obama the authority to launch an attack. It marked the first time in more than a decade — since a 2002 resolution that preceded the Iraq War — that members of Congress have voted to authorize military action.

Syrian Foreign Minister Walid al-Moualem will travel to Moscow for talks with his Russian counterpart Sergei Lavrov on Monday, the Russian Foreign Ministry said in a statement on Thursday. 

As leaders weighed possible U.S.-led military action, security sources in Baghdad told NBC News that Iraqi forces are stepping up security along the border with Syria in order to prevent "infiltration of armed groups into Iraqi territory" in the event of air strikes on Syria. 

Meanwhile, Lebanese militant group Hezbollah is preparing to defend Damascus from any possible invasion by rebels, according to a report in the Jerusalem Post.

Syria is defiant and will not change its position “even if there is World War III,” its deputy foreign minister reportedly said Wednesday.

Faisal Muqdad insisted Syria’s government would counter any military action aimed at punishing the regime for the suspected use of chemical weapons, according to an interview with AFP cited by regional news outlet Al-Arabiya.

NBC News' Ghazi Balkiz, Zoheir Al-Beate and Heather Lacy and Reuters contributed to this report.