Tug-of-war as US, world leaders debate Syria attack - CNN

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(CNN) -- NATO said Monday it wants a "firm international response" to the use of chemical weapons in Syria. Rebels fighting the Syrian regime want action fast. And some U.S. lawmakers support President Barack Obama's call for military strikes.

"It would send a very, I would say, dangerous signal to dictators all over the world if we stand idly by and don't react," Secretary General Anders Fogh Rasmussen said.

But NATO itself won't take military action. And Syria's allies in the U.N. Security Council, Russia and China, are sure to block any U.N. effort.

Russia, which has major trade deals with Syria, is sending a delegation to Washington for "dialogue" with members of Congress, the Kremlin said Monday.

When the two sides share "opinions and arguments, then we'll better understand each other," said Valentina Matviyenko, speaker of the Federation Council, the upper house of parliament. "And I hope that the U.S. Congress will take a balanced position" -- and reject military intervention.

Matviyenko insisted there are no "strong arguments" for war.

Syria continues to insist it was not responsible for any chemical attack. A U.S. attack on Syria, President Bashar al-Assad's regime says, would be illegal aggression.

U.S. Secretary of State John Kerry says there's an "overwhelming case" that Syria used chemical weapons in an August 21 attack.

Blood and hair samples obtained from first responders through an "appropriate chain of custody" have "tested positive for signatures of sarin" gas, Kerry told CNN's "State of the Union" on Sunday.

It's unclear exactly how the U.S. obtained the material independently of the United Nations.

The attack killed more than 1,000 people -- perhaps more than 1,400, according to U.S. officials.

"We know that the regime ordered this attack, we know they prepared for it," Kerry said.

"We know where the rockets came from. We know where they landed. We know the damage that was done afterwards. We've seen the horrific scenes all over the social media, and we have evidence of it in other ways, and we know that the regime tried to cover up afterwards."

Britain was just as forceful a voice for military action, until its Parliament rejected the possibility. And France has said it won't act without the United States as a partner.

Obama: Many want action, 'nobody wants to do it'

So the world is looking to the United States, waiting to see whether it will act. And following Obama's last-minute decision to hold off until Congress weighs in, no such action is expected until after lawmakers reconvene from recess on September 9.

"(W)e are looking at the possibility of a limited, narrow act that would help make sure that not only Syria, but others around the world, understand that the international community cares about maintaining this chemical weapons ban and norm," Obama said Saturday.

He added that "part of the challenge that we end up with here is that a lot of people think something should be done, but nobody wants to do it."

Obama stressed his preference for multilateral action, but said "it is not in the national security interest of the United States to ignore clear violations of these kinds of international norms, and the reason is because there are a whole host of international norms that are very important to us."

Transcript: Obama's remarks on Syria

China 'gravely concerned'

Lawmakers are split, worried about whether military strikes could worsen the situation.

The conflicting concerns leave Washington in the middle of a tug-of-war, and facing the possibility that any military action it takes could be unilateral.

"We are gravely concerned that some country may take unilateral military actions," Chinese foreign affairs spokesman Hong Lei said Monday.

"We believe that any action taken by the international community should abide by the purposes and principles of the U.N. charter ... so as to avoid complicating the Syrian issue and bringing more disasters to the Middle East region."

NATO is prepared to protect Turkey, a NATO member, if Syria attacks it, Rasmussen said Monday. The alliance has deployed Patriot missiles to the country, he said.

But, he said, "I don't foresee any further NATO role in Turkey. It is for individual nations to decide how to react to what has happened in Syria."

The United Nations, meanwhile, said evidence that could show whether chemical weapons were used in Syria was being delivered to a lab on Monday. But a U.N. spokesman would not estimate how long it may take to get results. Even when results are released, they won't show who was responsible.

Russia: 'There are no such facts'

Russia rejects Kerry's claim that the U.S. already has answers.

"We absolutely were not convinced by that (evidence) that our American partners, as well as the British and the French, showed us," Russian Foreign Minister Sergey Lavrov said, according to the state-run RIA Novosti news agency.

"There are no facts, there's only talk about what we know for certain. When we ask for more detailed evidence, they say, 'You know, it's all secret, so we can't show you.' That means that there are no such facts."

Al-Assad's regime Monday asked U.N. Secretary General Ban Ki-moon "to shoulder his responsibilities for preventing any aggression on Syria," the state-run Syrian Arab News Agency reported.

The United Nations charter generally doesn't allow countries to attack other nations unless in self-defense or with approval from the U.N. Security Council.

Under U.S. law, Obama doesn't have to get Congress' approval to launch military action. The 1973 War Powers Resolution authorizes a president to initiate an attack as long as he notifies Congress within 48 hours. But internationally, a U.S. strike against Syria could be deemed illegal.

Obama faces legal challenges on Syria strike

Why China, Russia and Iran are standing by the Syrian regime

Five U.S. Navy ships are being positioned in the Red Sea, a U.S. official said Monday.

A second official said the aircraft carrier USS Nimitz is not expected to participate in combat operations over Syria, but that the ship is there for a greater U.S. military presence in the region -- even as the possibility of a U.S. missile strike appears to be delayed.

U.S. Marines site hacked

The pro-Assad Syrian Electronic Army appears to have hacked the U.S. Marines recruitment website, marines.com, and posted a letter urging Marines not to attack Syria.

"Dear US Marines, This is a message written by your brothers in the Syrian Army, who have been fighting Al Qaeda for the last 3 years," the message states. "... Obama is a traitor who wants to put your lives in danger to rescue Al Qaeda insurgents."

The message ends by saying, "You're more than welcome to fight alongside our army rather than against it. Your brothers, the Syrian army soldiers. A message delivered by the SEA."

Al Qaeda-linked militants, including the al-Nusra Front, are among the opposition groups in Syria. Analysts fear a U.S. strike on the Syrian regime could help bolster al Qaeda.

Syria missile strike: What would happen next?

'Red line' debate: Are chemical weapons worse?

Reports: Sarin's been used in Syria before

World leaders have said previously that sarin has been used in the Syrian civil war.

In April, the United States said it had evidence sarin was used in Syria on a small scale.

In May, a U.N. official said there were strong suspicions that rebel forces used the deadly nerve agent.

In June, France said sarin had been used several times in the war, including at least once by the Syrian regime.

But the August attack was by far the deadliest. "This is such a blatant example, we can't pretend not to see it," says Michael Rubin, a former Pentagon official now with the American Enterprise Institute

No end to the bloodshed

While world leaders grapple with what to do about Syria, the reports of carnage on the ground keep rising.

At least 118 people were killed across Syria on Sunday, including 13 children, the opposition group Local Coordination Committees of Syria said.

At least 20 rebels were killed Monday in an army ambush in Adra, northeast of Damascus, the opposition Syrian Observatory for Human Rights said.

The United Nations has said more than 100,000 people -- including many civilians -- have been killed since a popular uprising spiraled into a civil war two years ago.

CNN's Ashley Killough, Evan Perez, Sarah Chiplin, Barbara Starr, Dana Bash, David McKenzie, Khushbu Shah and Mohammed Tawfeeq contributed to this report.