President Donald Trump's National Security Advisor John Bolton reportedly asked for the Pentagon to provide military options for striking Iran.

The Pentagon regularly prepares all kinds of military options for all kinds of scenarios, many of which are not imminent at all, but this request reportedly rattled the war planners.

Experts say the response to Bolton's request suggests he had something extreme planned.

Bolton has long advocated war against Iran and even regime change, which likely would shock the Pentagon.

President Donald Trump's National Security Advisor John Bolton reportedly asked the Pentagon to provide military options for striking Iran, which experts say should have been standard procedure, but somehow managed to shock defense officials.

Bolton, who has long advocated for the US to bomb Iran and even institute regime change against its theocratic rulers, requested options to strike Iran after Tehran-linked militants mortared, unsuccessfully, a US embassy in Baghdad, the Wall Street Journal first reported Sunday.

"It definitely rattled people," an official told the Journal. "People were shocked. It was mind-boggling how cavalier they were about hitting Iran."

But according to Ned Price, former special assistant to President Obama on the National Security Council, Bolton's response to an attack on the US represents standard operating procedure.

Read more: The Trump administration has been itching for a fight with Iran, but Mattis held it back. Now he's gone.

"It should come as no surprise that our military planners have devised war plans for a range of scenarios across the globe. Anything less would be derelict on their part," Price told Business Insider.

"What makes this different, however, is that the White House — in the form of Bolton — ordered the Pentagon to present these plans in the heat of the moment following an attack on US facilities," Price continued. "That’s qualitatively different than the Pentagon undertaking contingency planning as a matter of course."

So what could Bolton have requested from the Pentagon that came as such a shock?

Airstrikes.

US jets fly over Iraq in the Gulf War. AP

According to Patrick Clawson, the director of research at the Washington Institute for Near East Policy, the Pentagon's shock likely came from an extreme request from Bolton: Airstrikes.

Clawson said it was natural for the US to look to retaliate against Iran after militants under its command attacked US personnel, but that the US had plenty of options, even military options, short of alarming.

For example, the US could have ordered the navy to intercept Iranian boats at sea that they suspect of arming Houthi rebels in Yemen as a measured military response that likely wouldn't shock many in the Pentagon, said Clawson.

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But the rattled response by Pentagon officials indicates that Bolton likely saw the attack in Baghdad as the start of a wider campaign against US citizens in the Middle East, and that Bolton sought a heavy-handed response.

"Airstrikes are a stupid idea," said Clawson. If Bolton requested options for airstrikes from the Pentagon, "somebody should come back and say that's a really dumb idea," he continued.

While the US has ample air power and could easily hit targets in Iran, Clawson said "the Iranians would be able to play that well with their domestic audiences and the international audiences, saying the Americans are warmongerers and erratic."

Furthermore, Iran has denied directing the strike in Baghdad, though the US reportedly assesses they did indeed order attacks on the US.

Iran controls vast proxy forces across Syria and Iraq, which they can control with some plausible deniability. REUTERS/Thaier Al-Sudani

Iran therefore has "plausible deniability" in the attacks, whereas airstrikes with US military jets do not afford that same deniability to the US, and would mark a large escalation, said Clawson.

Read more: Trump has his cake and eats it too with sanctions tanking Iran's economy and oil staying low

"It’s the job of the Pentagon to have off-the-shelf options ready, but it’s the role of those in charge of policy — including the national security advisor — to ensure we employ force prudently and only as a last resort," said Price.

The Trump administration has actually enjoyed some success in punishing Iran for its regional behavior and rallying support from Europe, despite its controversial withdrawal from the Iran deal.

But a direct air strike on Iran in response to a failed mortar attack that injured no one could easily trigger an all-out war across the region, and easily send chills down spines among Pentagon warplanners.