Don Lee and W.J. Hennigan contributed to this report / Los Angeles Times (MCT)

President Barack Obama plans to address the nation today to outline a broader offensive against Sunni militants in the Middle East, a move welcomed by a number of key congressional leaders who have come to view the extremist group Islamic State (ISIS) as an increasingly menacing threat to the U.S.

Dr. Jeffery Cummins, a political science professor at Fresno State, said he thinks the president will outline a plan for dealing with ISIS, something critics say the Obama administration has lacked thus far.

“I expect him to emphasize the serious threat that ISIS poses to American allies and American interests and to outline a specific strategy for how the United States is going to establish a coalition and respond to ISIS’ aggression,” Cummins said.

“I think he’ll be pretty clear that he wants to stop short of sending in U.S. troops, with the exception of special forces and advisers to Iraq,” he said.

Foreshadowing his remarks in an interview that aired Sunday on NBC’s “Meet the Press,” Obama said it was time for the U.S. to “start going on some offense” to beat back ISIS fighters.

“I’m preparing the country to make sure that we deal with a threat,” Obama told NBC.

Since Aug. 8, the U.S. has conducted 143 airstrikes on ISIS targets in Iraq, actions Obama said were designed to protect people against genocidal attacks and to safeguard key property including the Mosul dam on the Tigris River.

Whether Congress will actually get to vote on Obama’s plan is uncertain. Congressional leaders have said they want Congress to be consulted, but they have not committed to a vote.

If it chooses to not to seek approval from Congress for military strikes in Syria and Iraq, the Obama administration will likely cite the Authorization for Use of Military Force Against Terrorists (AUMF) as legal justification for its actions, said Dr. Russell Mardon, a professor of political science at Fresno State.

According to the AUMF, signed in the wake of the September 11 attacks, the president has broad authority to use military force against terrorist threats.

“At least that is the way it’s been interpreted,” Mardon said, “the resolution, which authorized Bush to go into Afghanistan, authorizes [Obama] to go after all terrorist organizations connected with this act of terror. So that’s interpreted by Bush, then Obama, to mean anyone who’s an Islamic enemy.”

While Obama may have to justify his actions to the public, under current interpretations of the law, his military actions in the area are already legally justified, Mardon said.

On Tuesday, Obama approved sending 350 additional troops to Baghdad to increase diplomatic security for State Department officials at the Baghdad embassy compound and its support facilities.

There were about 200 to 300 U.S. military personnel in Iraq in mid-June. As ISIS grew in numbers, seized Mosul and began to advance toward the Iraqi capital, the administration began sending more forces to the country. With the 350 newly announced personnel, the size of the U.S. contingent will have increased to 1,113.

Despite his actions thus far, Obama has been criticized by some for failing to set a clear strategy on how to deal with ISIS, reflecting his reluctance to commit American forces to another war in Iraq. In the wake of the militants’ attack on minority Yazidis in Iraq and the beheadings of two American journalists, there have been growing calls from Congress and others for more aggressive action.

“What I want people to understand is that over the course of months, we are going to be able to not just blunt the momentum” of the militants, Obama said on NBC on Sunday. “We are going to systematically degrade their capabilities. We’re going to shrink the territory that they control. And ultimately, we’re going to defeat them.”

Although Obama said there would be a “military element” to the strategy, he added that “this is not going to be an announcement about U.S. ground troops.”

Among those in Congress welcoming such action was Sen. Dianne Feinstein, D-Calif., who chairs the Senate Intelligence Committee.

“I think that this is a major change in how ISIS is approached,” she said Sunday on CNN’s “State of the Union,” noting the coalition that the U.S. has forged with a number of allies, including some Middle Eastern countries, to counter the militant fighters.

“It is overdue,” she said, “but the president is now there, and I think it’s the right thing for America.”

Feinstein said she supported deploying the American military’s special operations forces and cracking down on sources of ISIS, among other more aggressive actions.

“ISIS is a major threat to this country in the future,” she said, noting that she believed the group was seeking to advance to Baghdad and to attack the U.S. Embassy there.

Senate Minority Leader Mitch McConnell, R-Ky., said in a statement that the ISIS threat is “real and it’s growing.” He urged Obama to “exercise some leadership” and to engage Congress with “a strategic plan.”

As the Obama administration seeks to put together a coalition to act against ISIS, Nabil Elaraby, the secretary-general of the Arab League, provided encouragement Sunday.

Elaraby told member foreign ministers gathered in Cairo that Arab states must unite to confront the threat posed by ISIS, which has seized large chunks of territory in Syria and Iraq, killed thousands of adherents to non-Sunni religious faiths, threatened Iraq’s government and the semiautonomous Kurdish region and beheaded two American journalists.

Western action against ISIS would be greatly eased by an Arab call for joint action, Elaraby told the ministers, citing previous accords under which member states would defend one another.

U.S. Central Command, which oversees military operations in the Middle East, said the strikes near the Haditha Dam destroyed eight ISIS vehicles ”” two of which carried anti-aircraft artillery ”” a command post and two fighting positions.

The dam is on a road about 100 miles from the border with Syria. It is the second-largest hydroelectric contributor in the power system in Iraq, the Pentagon said.

In addition, a military aircraft conducted one airstrike against an ISIS target near the Mosul dam Saturday. U.S. air support there last month helped Iraqi Kurdish peshmerga forces take back control of the dam, which is still under attack.

Both the Arab world and Western nations have been groping for a means of responding to ISIS, which has eclipsed al-Qaida in its radicalism, degree of on-the-ground military effectiveness and extent of territory captured.

Arab League leader Elaraby, in his comments Sunday, appeared to pave the way for Arab agreement to a Western intervention, noting that a “comprehensive confrontation” was needed to cope militarily with the threat posed by ISIS.

“What is happening in Iraq, and the presence of an armed terrorist group that not only challenges the state authority but its very existence and that of other countries … is one of the examples of the challenges that are violently shaking the world,” he told the gathering, according to The Associated Press.