US President Barack Obama speaks about the situation in Iraq in the State Dining Room at the White House in Washington, DC, August 7, 2014. Obama said he authorized air strikes and relief supply drops in Iraq to prevent 'genocide' by Islamist extremists against minorities. 'We can act, carefully and responsibly, to prevent a potential act of genocide,' Obama said, in an address as he announced military action. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

WASHINGTON -- The White House gave vague assurances on Friday that U.S. military involvement in Iraq will be limited in nature, seeking to ease political and public concern about Americans being drawn back into another war.

During his daily briefing, White House press secretary Josh Earnest repeatedly stated that the U.S. would not engage in "prolonged" efforts to beat back the Islamic State, the militant group formerly known as ISIS. But Earnest wouldn’t define what the administration viewed as prolonged, and, notably, he told reporters an end date hasn't been set for military operations, which began on Friday morning with two airstrikes.

"The president has not laid out a specific end date," Earnest said. "Those kind of decisions are evaluated regularly and are driven by the security situation on the ground, both as it relates to the safety and security of the American personnel but also as it relates to supporting the ongoing efforts of both Kurdish security forces and Iraqi security forces."

Earnest acknowledged the tension between President Barack Obama’s unwillingness to be dragged back into a protracted war and the urgent need to provide humanitarian aid to civilians and protect American interests in Iraq. The issue is complicated further by the president's own history with Iraq, having been elected to the White House in large part on a promise to end U.S. involvement there.

Earnest said repeatedly that air strikes will be "very limited in scope." Their primary goal, he said, is to protect U.S. personnel in the area from encroaching Islamist militants and to ensure that food and water are provided to tens of thousands of stranded Iraqi Yazidis, a religious minority that the militants are targeting.

"There is not a timeframe that I can share right now," he said, when pressed on how long it would all last. "I'm not in a position to offer a specific date [of withdrawal], but I am able to offer a specific presidential commitment that a prolonged military conflict that includes U.S. involvement is not on the table here."

Even without a clear endgame, the president currently enjoys broad support on Capitol Hill for U.S. military engagement in Iraq. House and Senate Democrats have almost unanimously signed off on Obama's decision to authorize air strikes there. As of Friday afternoon, the lone skeptics who have released public statements are Sens. Richard Blumenthal and Chris Murphy, both Connecticut Democrats.

"I oppose open-ended military commitments, which the President's actions in Iraq could become," Blumenthal said. "Humanitarian relief is necessary to prevent genocide and provide food and water to meet an urgent emergency, but the President owes the American people a better, fuller explanation of the scope and strategy of military actions."

“Like President Obama, I was elected to end America’s recent history of military hubris in the Middle East,” Murphy said. “The president has stated that his goals for immediate humanitarian and military action in Iraq are extremely limited -- to prevent a genocide of the Yezidi community and protect American personnel from imminent harm. These are legitimate reasons for action, but the president needs to better explain how this intervention is strictly time and scope limited.”