(CNN) -- Syrian President Bashar al-Assad warned Monday in an interview with CBS that his country will lash out in potentially unpredictable ways if struck over a chemical weapon attack, saying the West does not have "a single shred of evidence" to prove the claim his government was responsible.
"You should expect everything," he told interviewer Charlie Rose, sidestepping the question of whether he would use chemical weapons against Western forces.
"That depends," he said. "If the rebels or the terrorists in this region or any other group have it, it could happen."
He denied responsibility for the August 21 attack.
If United Nations weapons inspectors confirm the use of chemical weapons in Syria, it would mark an "abominable crime" deserving of international response, Secretary-General Ban Ki-moon said Monday in a briefing with reporters.
U.S. President Barack Obama has been at the forefront of calls for a military response to Syria's alleged use of chemical weapons in the attack, which U.S. officials estimate killed more than 1,400 people.
French intelligence believes al-Assad ordered the strike because he feared a major rebel attack from the suburbs that could have endangered his control of Damascus and the route leading to the city's airport, according to a French Defense Ministry official who brief reporters on background Monday.
A German newspaper, however, reported Sunday that German intelligence intercepted communications that indicate al-Assad had repeatedly denied his military approval for chemical attacks.
In addition to Obama, French President Francois Hollande also supports a military response but widespread support elsewhere for an attack has been lacking.
British lawmakers voted to preclude their military from participating in any strike, and polls in France and the United States reveal little enthusiasm for military action.
U.S. British and French leaders have argued that failing to respond to such an attack, which violates international conventions, would invite more use of chemical weapons and weaken international resolve against the use of chemicals on the battlefield.
"And the question for all of us is, what are we going to do about it?" U.S. Secretary of State John Kerry said Monday from London. "Turn our backs? Have a moment of silence? Where a dictator can with impunity threaten the rest of the world that he's going to retaliate for his own criminal activity because he's being held accountable?"
"We live in a dangerous world as it is, folks. And that kind of threat is nothing different from the kind of threat we face every single day," he said. "And if we don't stand up to it, we'll face it more, and they will think they can intimidate anybody."
In the CBS interview, al-Assad said members of Congress contemplating authorizing an attack on Syria should realize it would only damage U.S. interests.
"So the question they should ask themselves, what do wars give America? Nothing. No political gain. No economic gain. No good reputation. The credibility is at an all-time low. So this war is against the interests of the United States," he told CBS.
"Why? This is the war that's going to support al Qaeda and the same people that kill Americans on the 11th of September," he said.
Who ordered strike?
Syrian and Russian officials have blamed rebel forces for the August chemical attack.
On Sunday, the German Bild am Sonntag newspaper reported that communications intercepted by German intelligence aboard a ship off the Syrian coast suggest al-Assad may not have approved chemical attacks.
Citing unidentified high-level security sources, the newspaper said German intelligence had intercepted communications indicating Syrian military commanders had asked al-Assad for permission to use chemical weapons on nine separate occasions.
He denied those requests, according to Bild am Sonntag.
The German intelligence service, BND, declined to comment when contacted Monday by CNN regarding the account.
Russians calls for talks
Russian Foreign Minister Sergey Lavrov told reporters Monday that Russia will urge Syria to put its chemical weapons supply under international control if it doing so would avert U.S. military action.
Earlier, he called for international talks in Moscow to avert a military strike and end Syria's two-year-old conflict.
Sergey Lavrov, speaking in Moscow alongside his Syrian counterpart, blamed U.S.-backed rebels in Syria for preventing a peace conference in Geneva.
Kerry argued al-Assad won't negotiate without a strong international response.
"If one party believes he can rub out countless numbers of his own citizens with impunity ... he will never come to a negotiating table," Kerry said in London.
But Lavrov told reporters in Moscow that Syrian Foreign Minister Walid Moallem "said quite clearly Damascus is ready to participate in a positive way" in negotiations.
Lavrov said the Russian government would work with other nations to promote negotiations, "and if we can understand these contacts will help, then we can invite all those interested in the world to Moscow."
Kerry: Strike or no, political solution required
Kerry rejected arguments that rebels could have launched the attack, saying those groups don't have the scientific or military capability to deliver such weapons.
He also repeated American claims that the rockets used in the August 21 attack near Damascus were launched from regime-controlled territory.
Despite the need for a military response, Kerry said U.S. officials believe arms aren't the answer to the Syrian conflict, which the United Nations estimates has left more than 100,000 people dead.
Kerry said the United States still supports a future round of talks in Geneva.
"The end to the conflict in Syria requires a political solution." he said. "There is no military solution."
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