The US National Security Council set out plans for war on Iran last year, according to current and former American officials.

The officials told The Wall Street Journal that the proposals unsettled the State Department and Pentagon. The request came after three mortars were fired on the “Green Zone” in Baghdad, Iraq, where the US Embassy is located. The attack was allegedly by a group aligned with Iran.

National Security Advisor John Bolton — a hardliner who has previously pressed for war on the Islamic Republic, including in a 2015 opinion piece in The New York Times — convened a series of meetings to discuss military options.

A “former senior Administration official” said, “It definitely rattled people. People were shocked. It was mind-boggling how cavalier they were about hitting Iran.”

The Pentagon complied with the NSC request for plans. But Defense Secretary Jim Mattis and other military leaders firmly opposed implementation, saying the attack was insignificant, according to Pentagon officials.

A “senior American official” said a strike could have led to an Iraqi order for all US personnel to the country.

It is unclear if the plans were ever presented to the White House or if Donald Trump knew of the discussions.

“People familiar with the debate” said Mattis argued against US strikes on Iranian and Russian personnel in Syria, followed a chemical attack in April 2018 by pro-Assad forces on opposition territory near Damascus. Trump adopted a more limited set of raids on three facilities connected with the Assad regime’s chemical weapons program.

The attack on Baghdad’s Green Zone was on September 6, with a Shia militia close to Tehran taking responsibility. Two days later, rockets landed near the US Consulate in Basra, Iraq’s second city, with no group claiming the attack.

About that time, Bolton used a speech to warn Iran there would be “hell to pay” if the US or its allies were attacked. His deputy Mira Ricardel said the Iraq incidents were an “act of war” and Washington had to respond decisively.

The White House issued a two-paragraph statement on September 11, “The United States will hold the regime in Tehran accountable for any attack that results in injury to our personnel or damage to United States government facilities.”

Two weeks later, Pompeo said on CNN, “Iran will be held accountable for those incidents [in Iraq]….They’re going to be held accountable,” Mr. Pompeo replied. “If they’re responsible for the arming and training of these militias, we’re going to go to the source.”

But Ricardel was forced out of her post in November after a row with Melania Trump, including over airplane seating for Trump’s trip to Africa.