"We will be stronger as a country in our response if the president and Congress [do] it together," Obama said Wednesday during a news conference in Stockholm with Swedish Prime Minister Fredrik Reinfeldt. "I think it's important to have Congress' support on it."
Obama said he believes Congress will approve his authorization request to conduct limited missile strikes on Syria in response to evidence that forces loyal to President Bashar Assad used chemical weapons on Syrians.
"As commander in chief I always preserve the right and the responsibility to act on behalf of America's national security," Obama said in response to a question about what would happen if Congress fails to approve the strike. "I don't believe that I was required to take this to Congress. But I did not take this to Congress because I think it's an empty exercise."
In Washington, members of several congressional committees returned a week early to take testimony on the authorization request. Congressional leaders pledged to take up the matter as soon as Congress officially returns to Washington from its August recess next week.
Obama was in Sweden to meet Reinfeldt and a dinner with Nordic leaders before traveling to a two-day Group of 20 summit in St. Petersburg, Russia, that begins Thursday.
Reinfeldt said Sweden condemns the use of chemical weapons in Syria "in the strongest possible terms. It's a clear violation of international law."
While saying those responsible for the attacks should be held accountable, Reinfeldt said Sweden believes "serious matters concerning international peace and security should be handled by the United Nations."
"But I also understand the potential consequences of letting a violation like this go unanswered," he said. "In the long-term, I know that we both agree that the situation in Syria needs a political solution."
Obama originally was to meet with Russian President Vladimir Putin ahead of the summit, but that visit was canceled over conflicts about Syria and Russia's refusal to return National Security Agency leaker Edward Snowden to the United States, granting Snowden temporary asylum.
Noting that "we've kind of hit a wall" in terms of improving relations with Russia.
"But I have not written off the idea that the United States and Russia are going to continue to have common interests, even as we have some very profound differences on some other issues," Obama said.
"One area where we've got a significant difference right now is the situation in Syria. Russia has a long-standing relationship with the Assad regime," Obama said. "And as a consequence, it has been very difficult to get Russia working through the [United Nations] Security Council to acknowledge some of the terrible behavior of the Assad regime and to try to push toward the kind of political transition that's needed in order to stabilize Syria."
"If you, in fact, want to end the violence and slaughter inside of Syria, then you're going to have to have a political transition, because it is not possible for Mr. Assad to regain legitimacy in a country where he's killed tens of thousands of his own people," Obama said. "That will not happen."
Putin, so far "has rejected that logic," Obama said, noting that every time the U.N. Security Council has considered resolutions condemning Syria, "it has been resisted by Russia."
Obama also said the United States wants "to join with the international community" in an "effective response" to the use of chemical weapons in Syria, noting that he respects the U.N. process.
Reinfeldt said he and Obama also discussed other issues, such as business ties between the two countries, trade, the global economic situation and climate change.
"As you all know, this is a historic event, the first bilateral visit ever by a president of the United States to Sweden," Reinfeldt said. "Our societies are founded on the same core values: democracy, respect for human rights and rule of law. All these values are at the heart of the deeds of our value of life."
Later Wednesday, Obama visited the Great Synagogue and Holocaust Memorial and toured the Royal Institute of Technology, a research facility in Stockholm.
At the Great Synagogue, Obama paid tribute to Swedish businessman and humanitarian Raoul Wallenberg, widely celebrated for his efforts to rescue Jews -- estimated between tens of thousands and about one hundred thousand -- Nazi-occupied Hungary during the Holocaust from Hungarian Fascists and the Nazis later in World War II.
"Wallenberg's life is a challenge to us all -- to live those virtues of empathy and compassion, even when it's hard, even when it involves great risk," Obama said.
"Today we stand in awe of the courage of one man who earned his place in the Righteous Among the Nations" by Israel, Obama said. "And we pray for the day when all peoples and nations find the same strength -- to recognize the humanity that we share, and to summon in our own lives our capacity for good; to live with tolerance and respect; to treat everyone with dignity, and to provide our children with the peace that they deserve."
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