President Barack Obama last week approved limited airstrikes against Islamic State fighters, whose rapid rise in June plunged Iraq into its worst crisis since the end of 2011, when U.S. troops withdrew from the country after eight years of an unpopular war. Obama said the current military campaign would be a "long-term project" to protect civilians from the deadly and brutal insurgents.
Sen. Lindsey Graham, R-S.C., said the militants threaten not just Iraqis but also Americans. He said Obama's strikes were insufficient to turn back the militants and were designed "to avoid a bad news story on his watch."
"I think of an American city in flames because of the terrorists' ability to operate in Syria and in Iraq," said Graham, a reliable advocate for U.S. use of military force overseas.
"They are coming here," Graham later added about the militants. "This is just not about Baghdad. This is just not about Syria. It is about our homeland."
Graham added that if Islamic State militants attack the United States because Obama "has no strategy to protect us, he will have committed a blunder for the ages."
A close White House ally, Democratic Sen. Dick Durbin of Illinois, said Islamic State fighters are a "growing and troublesome" threat. But he added, "We must not send the troops."
"The big question is: What can the United States do to stop it?" Durbin asked.
American airstrikes have included fighter pilots and drones near Irbil, the capital of the Kurdish region in northern Iraq, as recently as Sunday. The strikes are aimed at limiting Islamic State fighters' advances and helping Iraqi forces take back control. U.S. and Iraqi aircraft also have dropped humanitarian aid for the minority Yazidis, thousands of whom have been stranded on a scorching mountaintop since the Islamic militants seized Sinjar, near the Syrian border, last week.
A breakdown in talks between Washington and Iraqi Prime Minister Nouri al-Maliki that would have allowed U.S. troops to remain in Iraq collapsed in 2008, and Obama withdrew troops in 2011 after eight years of war.
Al-Maliki now is under mounting pressure to step aside, including from U.S. lawmakers.
"The collapse of Mosul was the not a result of a lack of equipment or a lack of personnel. It was leadership collapse," said Sen. Jack Reed, D-R.I.
Critics say the Shiite leader contributed to the crisis by monopolizing power and pursuing a sectarian agenda that alienated the country's Sunni and Kurdish minorities.
The Islamic State group, which some lawmakers refer to as ISIS, or the Islamic State of Iraq and Syria, is "getting stronger all the time," warned Sen. John McCain, R-Ariz.
"They have attracted 1,000 young men from around the world who are now fighting on their side," McCain added. "This ISIS is metastasizing throughout region, and their goal, as they've stated openly time after time, is the destruction of United States of America."
Lawmakers from both parties largely agreed that a war-weary America has little appetite to send military forces back to Iraq.
Sen. Ben Cardin, D-Md., said Iraqis need to handle their domestic security.
"There is not a U.S. military solution to this issue," Cardin said.
"We will not become the Iraqi air force," he added. "I don't think we can take out ISIS from a military point of view, from the use of our air strikes."
But Rep. Peter King, R-N.Y., said popular opinion should not drive national security decisions.
"I am saying we should do whatever we have to do," King said.
Graham and Cardin spoke to "Fox News Sunday." Durbin and King appeared on NBC's "Meet the Press." Reed was interviewed on CBS' "Face the Nation." McCain was a guest on CNN's "State of the Union."