U.S. Secretary of State Hillary Rodham Clinton on Sunday acknowledged deep differences with Russia over how to handle the crisis in Syria, saying she would continue to try to convince Moscow to back increased international pressure on Syrian President Bashar Assad even if such a step is unlikely.

A day after Russia soundly rejected her call for U.N. sanctions to be imposed on Syria if Assad refuses to stop fighting and relinquish power, Clinton said she was "realistic" in her approach. She said that if the Russians refused to go along the United States and its friends would boost their support for the Syrian opposition.

"The United States disagrees with the approach on Syria," she told reporters at a news conference at the end of the annual Asia Pacific Economic Cooperation forum summit where she was filling in for President Barack Obama. "We have to bring more pressure to bear on the Assad regime to end the bloodshed and begin a political, democratic transition."

The Obama administration has been hoping to jack up pressure on Assad at the upcoming United Nations General Assembly session and potentially introduce a new U.N. Security Council resolution that would include sanctions. Russia and China have blocked three previous similar resolutions because they could lead to sanctions.

In discussions with Russian President Vladimir Putin and Foreign Minister Sergey Lavrov, Clinton said she had underscored the resolution "will only be effective if it includes consequences for non-compliance."

"There is no point in passing a resolution with no teeth because we have seen time and time again that Assad will ignore it and keep attacking his own people," she said.

But, she allowed that convincing the Russians would be a tough, if not impossible sell.

"We have to be realistic," she said. "We haven't seen eye-to-eye with Russia on Syria."

"That may continue, and if it does continue, then we will work with like-minded states to support the Syrian opposition to hasten the day when Assad falls and to help prepare Syria for a democratic future and help it get back on its feet again," she said.

After meeting Clinton on Saturday, Lavrov said bluntly Russia opposes penalties against the Assad government, in addition to new ones against Iran over its nuclear program, in part because they harm Russian commercial interests.

"Our American partners have a prevailing tendency to threaten and increase pressure, adopt ever more sanctions against Syria and against Iran," Lavrov said. "Russia is fundamentally against this, since for resolving problems you have to engage the countries you are having issues with and not isolate them."

Unilateral U.S. sanctions against Syria and Iran increasingly take on an extraterritorial character, directly affecting the interests of Russian business, in particular banks, he said.

"We clearly stated that this was unacceptable, and they listened to us. What the result will be, I don't know," Lavrov said.

Clinton had told Lavrov that the Security Council needs to do more to send "a strong message" to Assad, given the escalating level of violence in Syria, said a senior U.S. official, adding that the council risks "abrogating its responsibility" if it fails to act. The official spoke on condition of anonymity because the conversation was private.

Russia and China have blocked three Security Council resolutions that would have punished Syria if the Assad government did not accept a negotiated political transition. Clinton said in Beijing this past week that the U.S. was "disappointed" by the vetoes.

She had earlier called the actions "appalling" and said they put Russia and China on the "wrong side of history." That assertion was rejected by Chinese Foreign Minister Yang Jiechi at a news conference with Clinton on Wednesday, when Yang said history would prove China's position to be correct.

The question of sanctions against Syria and Iran will be a main topic of conversation among officials later this month at the U.N. General Assembly.

Despite Russia's refusal to join the U.S. and its allies in seeking more pressure against Syria and Iran, Clinton said the Obama administration wants Congress to remove Russia from a 1974 law that denies Russia normal trade relations with the U.S because of Soviet-era laws restricting the emigration of Jews.

Now that Russia has joined the World Trade Organization, membership that the United States long supported, Clinton said it would be "ironic" if American businesses were unable to do business in Russia because of U.S. law.