Editor's Note: (Peter Bergen is CNN's national security analyst, a vice president at New America and a professor of practice at Arizona State University. His new book is "Trump and His Generals: The Cost of Chaos." The opinions expressed in this commentary are his own. View more opinion articles at CNN.)
(CNN) The targeted killing of Iranian Gen. Qasem Soleimani is arguably the most consequential American intervention in the Middle East since George W. Bush authorized the ill-fated invasion of Iraq in 2003.
Was this a bold move or a reckless gamble?
We are beginning to get an answer to this question. Already the killing of Soleimani precipitated Iran to announce on Sunday that it was suspending commitments it made in its 2015 nuclear agreement that capped its centrifuge allowance.
Inspectors of the International Atomic Energy Agency had repeatedly found that Iran was adhering to that agreement.
Now there is the prospect that the mullahs who run Iran could try to seek a nuclear weapon.
An Iran armed with nuclear weapons is clearly not preferable to an Iran without nuclear weapons, the latter of which we've seen since 2015 when the nuclear agreement was signed.
Also on Sunday the Iraqi Parliament set in motion the process to expel American troops from Iraq, which has been a long-term goal of the Iranians.
The last time that American troops pulled out of Iraq was at the end of 2011 under the Obama administration. Three years later ISIS took over much of Iraq.
Trump had a bizarre reaction to the vote by the Iraqi Parliament telling reporters on Sunday; "If they do ask us to leave, if we don't do it in a very friendly basis, we will charge them sanctions like they've never seen before, ever. It'll make Iranian sanctions look somewhat tame." Iraq is a US ally that was instrumental in the defeat of ISIS.
The Iraqi protests against Iranian influence in Iraq that took place in November have now been replaced by protests against the United States.
Similarly, recent protests in Iran against the regime have been replaced by protests against the United States.
And now we are teetering on the edge of a war between the US and Iran. Iran's top military adviser told CNN that revenge would be taken for Soleimani's death by attacks on American "military sites."
And there are many of those to choose from in the region, for instance, in Afghanistan, Iraq, and Syria to name just three countries where Iran wields considerable influence.
Meanwhile Trump has taken to Twitter to threaten war crimes against the Iranians in the form of strikes aimed at Iran's cultural patrimony; a form of warfare that we associate with ISIS, not the US military.
We are now exactly where Trump's former Secretary of Defense, Jim Mattis, worried that we would be.
During the course of reporting my new book, "Trump and His Generals: The Cost of Chaos" I discovered that Mattis repeatedly stonewalled or slow-rolled military options on Iran requested by the White House fearing that Trump might embroil the United States in a war with the Iranians.
Mattis told senior officials in the Trump administration, "We have to make sure reason trumps impulse."
White House officials realized that Mattis believed Trump was a loose cannon and that Mattis didn't want to enable any bad decisions by providing military options that Trump could then seize upon.
According to the New York Times, this is exactly what happened with the decision to kill Soleimani. Soleimani's killing was on a menu of options presented to Trump following the killing of a US contractor last month in Iraq that the US government blamed on an Iran-backed Shia militia.
The President seized on this most extreme option leaving top Pentagon officials "stunned' and "flabbergasted," according to the Times.
Also, Trump can no longer draw on the considerable expertise about the Middle East possessed by Mattis, as well as his former chief of staff, Gen. John Kelly, and his former national security adviser, Lt. General H.R. McMaster, all of whom served in Iraq. These generals all resigned or were pushed out of office because they were willing to disagree with Trump about policy matters.
Mattis's replacement as Secretary of Defense, Mark Esper, has no known expertise in the Middle East, nor does Trump's acting chief of staff, Mick Mulvaney, nor does his national security adviser Robert O'Brien. Nonetheless, Trump now seems increasingly confident in his own military judgments.
Trump should appoint advisers at the White House who can give him informed, expert advice about the likely fallout from his actions, which don't seem to have been well-considered when it came to ordering the death of Soleimani.
Would Trump listen to them? Who knows, but at least he would get a sense of all the different scenarios that might play out after such a consequential decision.