President Obama appears prepared to authorize U.S. military airstrikes in Syria as part of a more intensive campaign to defeat the Islamic State, and the White House does not believe it needs formal congressional approval to take action, according to people who have spoken with the president in recent days.

Obama discussed his plans in a dinner with a bipartisan group of foreign policy experts Monday night at the White House and made clear he believes he has the authority to attack the militant Islamist group on both sides of the Iraq-Syria border in order to protect U.S national security, multiple people who participated in the discussion said. The move to attack in Syria would represent a remarkable escalation in strategy for Obama, who has sought during his presidency to reduce the U.S. military engagement in the Middle East.

The Islamic State controls wide swaths of territory in both countries, but the United States has so far limited its military engagement to Iraq, as Obama has been reluctant to intervene in Syria's civil war.


President Obama speaks at a press conference on the second day of the NATO 2014 Summit at the Celtic Manor Resort in Newport, South Wales, on Sept. 5. (AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images)

As the president prepares to brief congressional leadership Tuesday and deliver a prime-time White House address to the American public Wednesday night, he is committed to taking the fight to the Islamic State "wherever their strategic targets are," said Michèle Flournoy, the former U.S. undersecretary of defense policy who was among those at the dinner.

"This is not an organization that respects international boundaries," said Flournoy, who left the Obama administration in 2012 and now serves as chief executive of the Center for a New American Security. "You cannot leave them with a safe haven. ... I expect him to be very candid."

There is no indication that a U.S. strike in Syria is imminent, and the Obama administration has signaled that a stepped up U.S. effort in Iraq, in conjunction with an international and regional partnership, is likely the first step in combating the Islamic State advances.

A White House official did not immediately reply to request for comment for this story. In an interview on NBC's "Meet the Press" last weekend, Obama said it was time for the United States to "start going on some offense" against the Islamic State.

At his daily briefing Tuesday, White House press secretary Josh Earnest said the Islamic State is "operating in a virtual safe haven in Syria. That’s a dangerous situation.”

White House press secretary Josh Earnest said at the daily briefing on Tuesday that the president would speak about the military and diplomatic roles the U.S. will take in supporting Iraqis against Islamic State militants in light of the swearing in of a new "inclusive Iraqi government." (AP)

Obama, who has been criticized for being too cautious by members of both political parties on Capitol Hill, is unlikely to lay out all the details of his plans to expand U.S. military engagement in the region during his speech on Wednesday, which will take place at 9 p.m. in the State Floor of the White House. Instead, he is expected to make his case for how targeted U.S. military force fits into his broader strategy to develop an international coalition and regional partners to attack the Islamic State in order to "degrade and destroy" its operations.

The president “thinks he has the legal authority he needs" to increase U.S. military engagement in both Iraq and Syria, said Jane Harman, president of the Woodrow Wilson International Center for Scholars, who attended the dinner with Obama. The White House's belief that it has authority to act is based on the reports Obama has filed with Congress under the War Powers Act and the earlier congressional authorization for the war in Iraq.

Over the past month, Obama has authorized airstrikes against the Islamic State in Iraq to defend U.S. personnel, help rescue members of a religious minority group trapped on a mountainside and defend strategic infrastructure, including two dams. He sent in U.S. troops to help protect the consulate in Irbil, but he has vowed not to send U.S. combat forces in the campaign against the Islamic State, after having withdrawn the remaining U.S. forces from Iraq several years ago.

Last year, Obama had decided to authorize limited airstrikes against Syrian President Bashar al-Assad, but the president ultimately chose to ask Congress to endorse the move with a formal vote. That effort failed and the U.S. did not intervene with direct military action. But the Islamic State's rapid advances into Iraq this summer and its brutal tactics, which included the beheadings of two U.S. journalists in the past month, has ramped up pressure on the administration to take stronger action.

Several prominent Republican members, including Sen. Robert Portman (Ohio), said they believe Obama can launch airstrikes to combat the militants in both Iraq and Syria without seeking a congressional vote.

“The president has authorization to act now,” Portman said in a phone interview Tuesday.

Portman said he remained “a little confused” about the administration's strategy, saying it has been slow to develop.

“It’s just a passive response. I think it’s a leadership deficit right now,” he said, adding that he appreciates that the White House has scheduled briefings for the full House and Senate membership over the coming days. “We are ‘leading from behind,’ to use the president’s words. By not leading, we are making it more difficult, and more costly.”

Obama's dinner with the group of foreign policy experts -- a gathering that former high-ranking officials in Republican administrations, including Richard Haass and Stephen Hadley -- was part of a concerted White House effort in recent months to expand its sphere of influence. Although the president has on a semi-regular basis invited in outside experts for conversations, the White House has shifted its tone in recent months amid a series of high-profile foreign policy crises, ranging from Russia's intervention in eastern Ukraine, the Israeli-Palestinian conflict in Gaza and the advance of the Islamic State deep into Iraq.

In private conversations, senior White House national security aides have expressed greater willingness to hear new ideas and solicit input in hopes of doing a better job of developing strategy and communicating it to the public, said several influential foreign policy experts that have talked with Obama advisers in recent months.

Harman described the dinner on Monday as “focused and thoughtful.” Over a dinner of d'anjou pear salad and Chilean sea bass, Obama, Vice President Biden and the outside experts engaged in a deep discussion of the options to combat the Islamic State, those who participated said.

“The president clearly brought his 'A' game to this dinner,” Harman said. “I certainly felt my views were solicited and heard. He was in intake mode.”

Obama was clear that he wanted general congressional support -- or "buy-in" -- for his plans, in part because the increased military campaign, including training of Iraqi military forces and other regional fighters to take on the Islamic State, will come with a significant price tag from the Pentagon and is likely to take several years, people involved in the dinner said.

The president believes that his strategy falls within his broader national security strategy, outlined last spring in a speech at West Point, to used targeted force and avoid having the U.S. military get pulled into long ground campaigns.

One former Obama administration official, who was not at the dinner on Monday, said that the president was committed to a strategy to strike the Islamic State "wherever they are. The bar for strikes in eastern Syria is higher than in western Iraq, and if you're a military planner you have to meet that threshold. But the fact that we're reportedly doing surveillance flights over Syria already -- you're not doing those things unless the military has already been asked to prepare a targets package."