Smoke rises from a oil refinery in Baiji in 2015. The Iraqi army and volunteer militia fighters, who are mostly Shi’ite, launched an assault on Wednesday to retake the city of Baiji in northern Iraq from Islamic State militants, an Iraqi military spokesman said. Picture taken October 14, 2015. REUTERS/Stringer

Republican presidential nominee Donald J. Trump said on Wednesday that the United States should “take the oil” in Iraq as part of the “spoils of war” and to keep it out of the hands of ISIS. “I’ve always said, shouldn’t be there, but if we’re going to get out, take the oil,” he said. “If we would have taken the oil, you wouldn’t have ISIS, because ISIS formed with the power and the wealth of that oil.”

When moderator Matt Lauer asked how, Trump said, “we would leave a certain group behind and you would take various sections where they have the oil.”

What would doing that actually involve? A supertanker-size set of problems.

The United States can’t just walk off with Iraq’s oil when it decides to get out. In 2015, Iraq produced about 4 million barrels a day, enough crude oil to fill more than 700 Trump Towers. Billions of barrels more sit underground in conventional reservoirs.  The International Energy Agency has estimated that Iraq could produce twice as much as it does currently — by 2035.

That means taking the oil would take decades. That might explain Trump’s suggestion that “a certain group” should be left behind to hold down parts of the country so that the United States could siphon off oil. What he didn’t say is that that group – undoubtedly U.S. soldiers — could be there quite a while.

In addition, Iraq’s oil wells and pipeline networks span the length of the roughly 700-mile-long country, from the border near Syria to Kurdish areas in the northeast to the giant fields in the south and the export facilities on the Persian Gulf.

A relatively modest U.S. force – meaning about 20,000 to 30,000 soldiers, according to Douglas Ollivant, a senior fellow at the New America Foundation who did military tours in Iraq — could occupy the area in the south where 85 to 90 percent of the oil lies. That would qualify as “spoils of war” Trump said he favored.

But securing the oil fields across the country to make sure ISIS couldn’t get its hands on any of it would require a force bigger than the one the Bush administration sent to take over the country. So far, ISIS has tapped into small oil fields in the north. The biggest was damaged in a U.S.-led air strike in August 2014. Currently ISIS is still producing a small amount from Iraq’s northern Qayara field and that’s been enough to help sustain the group.

“To ‘take the oil’ would require the United States to occupy Iraq.  We tried that after 2003 with something approaching 200,000 troops and it did not work,” said Andrew Bacevich, a retired colonel and professor of history and international relations at Boston University.  “What would effective occupation actually require?  A minimum of a half-million troops, perhaps more.”

Bacevich added, “Presumably, Trump would have them stay until the oil runs out, which would entail an occupation running into decades. The total cost?  Probably more than the value of the oil itself.  The whole idea is beyond goofy.”

The troops tasked with taking the oil would also be in even greater danger than before because the seizure of the oil could ignite broader opposition across all Iraqi political groups.

“You could probably secure the area if you’re willing to have a forever war and 19-year-old Americans sniped at by Iraqis,” said Ollivant,  a former National Security Council director on Iraq for Presidents Bush and Obama.

“Taking oil from the Iraqis is akin to taking oil from Texans, coal from West Virginians or timber from Oregonians. This is the stuff their economy is based on and they would probably fight to keep it,” added Ollivant, who is now a part-time consultant on development for U.S. firms and the Iraqi government in Baghdad and the provinces. “If someone came to my country and stole my oil I’d probably shoot at them too.”

There are legal issues as well. Seizing the natural resources of a sovereign nation after invading it would violate the Geneva Conventions. Indeed, that’s why the United States went to war with Iraq the first time: In 1990 Iraq invaded another sovereign country, Kuwait, to take its oil reserves.

“Under what possible legal regime could we hope to do this?” Ollivant asked.

“And we’re the only ones, we go in, we spend $3 trillion, we lose thousands and thousands of lives, and then, Matt, what happens is, we get nothing.” Trump said to Lauer. “You know, it used to be to the victor belong the spoils. Now, there was no victor there, believe me. There was no victor. But I always said: Take the oil.”

Not so simple, policy veterans say.  “I was on National Economic Council and National Security Council when we invaded Iraq,” said Robert McNally, now head of the Rapidan Group, an energy consulting firm. “We didn’t do it for Iraq’s oil. And we took pains to avoid even seeming like we were out to seize Iraq’s oil.”

Instead, he said, “We were hoping Iraq’s production would recover quickly. What mattered was use of those revenues to rebuild Iraq.” Reconstruction and a well-supplied oil market were the top goals, McNally said, adding “that is still what I think is the correct way to think about Iraq’s production.”

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