British Prime Minister David Cameron recalled Parliament on Friday to vote whether to join the growing coalition fighting the Islamic State in Iraq and the Levant (ISIL). The United Kingdom cannot "walk on by" the threat, Cameron said.

Congress may not walk on by either, but it chose the campaign trail instead of Capitol Hill. Voting on the most profound question of governance — war — will likely have to wait until after the midterms.

Once Congress does debate re-entering Iraq, it would be wise to also consider an exit strategy. And not just for U.S. forces — there should also be an acknowledgment of America's responsibility to protect Iraqi and Syrian soldiers, "moderate" rebels, and citizens who help U.S. forces.

To remind them of the stakes, Congress and President Obama should watch "Last Days in Vietnam." The riveting film, which will debut Oct. 3 at the Uptown Theater, chronicles the chaos, and courage, when Saigon fell in April 1975. Using news reports and never seen footage, interspersed with interviews of Vietnamese and American military and diplomatic personnel, the documentary depicts a split between Americans in Washington and Saigon on how to ensure the safety of South Vietnamese allies.

Back in the Beltway, Congress, wary of wading back into the quagmire it exited two years earlier, indifferently denies President Gerald Ford's request for $722 million in emergency military assistance. Ford, conversely, comes across as compassionate, and even passionate, about the people as well as the policy implications of abandoning allies.

But the real heroes were individuals who bucked institutions as powerful as the Pentagon, State Department and White House to save as many South Vietnamese as possible from the conquering Communist army. At great risk, using makeshift methods including "black operations," U.S. troops and diplomats took extraordinary steps that saved thousands of South Vietnamese from bleak fates under Communist rule.

"I think the film is a reminder of the human cost of war, which at times is easy to lose sight of when it feels remote for us," Rory Kennedy, producer and director of "Last Days in Vietnam," said in an interview. "We can forget about our responsibilities to the people on the ground, who when we leave are left behind."

Reflecting on that abandonment, Kennedy said that, "For many of us, Vietnam represents a very dark moment in our nation's history. Yet there are these stories of Americans and South Vietnamese who arguably risked their lives, and certainly their jobs, to rescue South Vietnamese."

"Last Days in Vietnam" captures some of these stories that captivated Kennedy. She said that she's always been fascinated with the war because her father, Robert F. Kennedy, "ran his last campaign in 1968 because he was so committed to getting out of Vietnam. … And we were on the brink of getting out of Iraq and Afghanistan, so I thought there might be lessons about getting out of Saigon 40 years ago."

There certainly are. And the link was amplified when the documentary debuted in Washington the same night that Obama addressed the nation about his strategy to "degrade and ultimately destroy" ISIL.

The crisis has sparked a foreign policy and political debate about whether withdrawing all U.S. combat troops from Iraq created, or contributed to, a vacuum that was filled by nihilists flying black flags.

Weighing in from the Brookings Institution, Michael O'Hanlon, director of research, Foreign Policy, said in an e-mail exchange that former Iraqi Prime Minister Nouri al-Malaki "produced the conditions for ISIL's rise, so the main responsibility is on him." O'Hanlon, a noted expert on diplomatic and military matters, added that, " … If we'd been around, we could have continued to exercise leverage, as he would listen to Americans at least to an extent. So it was a mistake to leave, even if largely/primarily an Iraqi decision."

O'Hanlon and many other foreign policy experts also think it would be a mistake to repeat the total pullout in Afghanistan, where this week a final power-sharing scheme was agreed to by Ashraf Ghani, who will be president, and Abdullah Abdullah, who will serve as a de facto prime minister. Both have indicated that they would sign a bilateral security agreement that would keep about 9,800 U.S. troops there.

Just as it initially was with Saigon, lost in discussions about military strategy are the moral dimensions of not protecting interpreters, drivers and others who helped U.S. forces.

"In Rory's film, I see the DNA of the tendency of what we do as a nation when we are done with the wars we grow weary of, but also the potential to do the right thing," said Kirk Johnson, founder of The List Project to Resettle Iraqi Allies. "Everyone knows the rooftop scene," Johnson said, referring to the iconic image of a departing helicopter in Saigon. "But what is less acutely understood is we ended up resettling roughly 1 million Vietnamese and Laotians in our country." That figure dwarfs the number of Afghans and Iraqis who have been granted asylum here, Johnson said, adding that the failure has been bipartisan.

"We've had two presidents basically hobbled by wishful thinking. [President George W.] Bush needed Iraq to seem like a success to justify the 'surge,' " Johnson said. "In a perverse echo affect, Obama needed Iraq to seem better than it was as well because we pulled out."

Reflecting on "Last Days in Vietnam," Johnson said that, "The Vietnam example is so powerful because it reminds us what the default pressure is — to leave these people behind. No one is going to be re-elected because they brought a bunch of refugees into this country. But when a president steps up like Ford did, we absolutely can be the Statue-of-Liberty-type of Americans we like to think of us as."

As the strikes on ISIL accelerate, Kennedy urges careful consideration of the long-term implications. "When we enter these engagements, conflicts, wars, whatever you want to call them, is when you have the most control. And when you start down that path is when you lose control …"

John Rash is a Star Tribune editorial writer and columnist. The Rash Report can be heard at 8:20 a.m. Fridays on WCCO Radio, 830-AM. On Twitter: @rashreport.