Sen. John Walsh (D-Mont.), rides the Senate subway Capitol Hill on June 3. (J. Scott Applewhite/AP)

The only military veteran of the Iraq war serving in the Senate said Wednesday that the financial and personal costs of sending U.S. troops back into Iraq would be too great and that Iraqis -- not Americans -- need to rise up to defend their own country.

Sen. John Walsh (D-Mont.) once served as adjutant general of the Montana National Guard and led more than 700 soldiers in Iraq from 2004 to 2005. The former lieutenant governor came to the Senate earlier this year as the successor to former senator Max Baucus (D-Mont.).

As the most junior senator in the Senate, Walsh is rarely seen or heard from, but Wednesday he delivered the Democratic counterargument to Republicans who in recent days have urged President Obama to use military action to target fighters from the Islamic State of Iraq and Syria (ISIS) and other insurgents.

The Pentagon’s top leaders warned Wednesday that airstrikes in Iraq would be fraught with complications and suggested that a rush to take such action could backfire.

In a speech Wednesday afternoon, Walsh agreed. With his son, Michael, who also served in Iraq, watching from the Senate Gallery, Walsh read aloud the names of the four men from his unit who were killed in action during the war. "There isn't a day that goes by when I don't think of those men and their families," he said.

"America cannot afford another Iraq financially or the human costs that are associated with war," he said later. "We did our job there, and we did it with honor and integrity, and our men and women should be very proud of their success, and the citizens of this country should be proud of the accomplishments of the men and women who served in our armed forces." But sending U.S. troops "into the middle of a civil war is not a solution," he said.

To his colleagues, Walsh urged "temperance as we navigate this difficult terrain, because I know that foreign policy failures made in Washington fall disproportionately on the backs of young men and women from small towns across Montana and across America."

To the Iraqi people, Walsh said it is time for them "to secure and defend their own nation, to embrace their own self-determination is the only path to a true and everlasting peace in Iraq."

And for those urging new military action, Walsh cited the troubles facing the Veterans Affairs Department as evidence of poor planning for the eight-year war in Iraq and ongoing war in Afghanistan. While policymakers worried about paying for training, deploying and caring for troops in battle, providing health care for returning veterans "is a cost that we sometimes overlook, because when our men and women return from Iraq, the war is not over. We will be dealing with this cost for many, many years."

"There are no easy answers to what's happening in Iraq, and I know that we will come together and come up with a solution, and I hope it's the right solution because these are very important times," Walsh added. "And who knows what will happen next?"