As the insurgency in Iraq threatens the stability of the Shiite-led government there, only 18 percent of Americans think the Iraq War was worth the costs, according to a new poll.

The CBS/New York Times poll asked if the costs of the Iraq invasion, including monetary and loss of American lives, were worth it. A record 75 percent of those surveyed said that it wasn’t worth the costs, up from 67 percent in November 2011 (just before the final withdrawal of US troops) and 45 percent in August 2003, five months after the invasion began.

“Our 2003 invasion of Iraq should be a warning that military force sometimes transforms a genuine problem into something worse. The war claimed 4,500 American lives and, according to a mortality study published in a peer-reviewed American journal, 500,000 Iraqi lives,” Nicholas Kristoff wrote in a New York Times op-ed. “Linda Bilmes, a Harvard expert in public finance, tells me that her latest estimate is that the total cost to the United States of the Iraq war will be $4 trillion.”

The survey released Monday found that 63 percent of Republicans and 79 percent each of independents and Democrats didn’t think the war was worth the cost.

As a major offensive by the al-Qaeda-inspired group Islamic State in Iraq and the Levant (ISIS, or ISIL) enters a second week in Iraq and hundreds of Iraqi soldiers have been killed as militants expand their control, the debate has begun on Capitol Hill and in the White House about what steps the US should take to prop up the government of Prime Minister Nouri al-Maliki.

On Thursday, President Barack Obama said that up to300 additional American military personnelwill head to Iraq and assume an advisory role there. The announcement comes only days after Obama said he was sending 275 armed troops to Baghdad as a security precaution. But he reiterated that no US troops will assume combat roles in Iraq, although the Pentagon is ready to take “prepared and targeted” military action overseas if necessary.

“I think most important is that we take direct action now against ISIS, marching down to Baghdad, and prevent them from getting into Baghdad,” Sen. Dianne Feinstein (D-Calif.) told The Hill, calling for drone or air strikes in Iraq.

US troops left Iraq at the end of 2011, and experts noted at the time that, while Obama kept his promise to end the war in Iraq, the US left without assurances that Baghdad could maintain security and order in the country – or build a firm political system. The poll found that, in light of the crisis occurring there now, Americans are torn on whether that was the right decision: 50 percent said the US should have removed all its troops from Iraq, while 42 percent said some US military members should have remained. In those households with veterans from the Iraq or Afghanistan Wars, 43 percent said troops should have stayed in Iraq.

Kristoff questioned whether US politicians had learned anything from the high cost of the Iraq War. “We financed a futile war that was like a Mobius strip, bringing us right back to an echo of where we started,” he wrote.

“We might have learned some humility. Yes, the military toolbox is handy and often useful. But one of the most basic lessons of international relations is a frustrating one: There are more problems than solutions,” he argued, calling out politicians like Feinstein, former Vice President Dick Cheney and former American envoy in Iraq Paul Bremer for their hawkish calls for military intervention.

The CBS poll shows that Americans support some forms of military re-involvement in Iraq, but there is no overwhelming mandate for any of the options, especially since half those polled think the US has no responsibility to curtail the recent violence in Iraq. A slim majority (51 percent) of respondents backed sending military advisers to Iraq, while 56 percent (including 69 percent of Republicans surveyed) endorsed the use of drones to target militants. A minority (43 percent) supported manned air strikes, but only 19 percent of respondents thought the US should send ground troops.

But regardless of the options, Americans are pessimistic about the outcome. “The poll also suggests the public views the situation in Iraq with some futility; most Americans do not think the U.S. can do something about the situation in Iraq. Fifty-seven percent think the situation there is beyond the control of the U.S., including majorities of all partisans,” CBS and the New York Times found.