Washington (CNN) Secretary of State Mike Pompeo and Attorney General William Barr said Monday that killing Iranian commander Qasem Soleimani was part of a larger strategy of deterrence, a shift from the Trump administration's previous rationale that the strike was carried out to prevent an "imminent" attack.

Barr's comments were particularly noteworthy as he attempted to push back on criticism over the administration's claim that Soleimani was planning attacks that posed an imminent threat, calling the concept "something of a red herring."

"I believe there was intelligence of imminent attack, but I do believe that concept of imminence is something of a red herring," he said during a press conference on last month's deadly shooting at a Naval Air Station in Pensacola, Florida.

"I think when you're dealing with a situation where you already have attacks underway, you know there is a campaign that involves repeated attacks on American targets, I don't think there's a requirement frankly for, you know, knowing the exact time and place of the next attack. And that certainly was the position of the Obama when it droned leaders of terrorist organizations," Barr added.

Pompeo, who has leaned heavily on the assertion that intelligence showed an imminent threat, did not mention that reasoning Monday during a speech at the Stanford's Hoover Institute.

"I want to lay this out in context of what we've been trying to do. There's a bigger strategy to this," the top US diplomat said. "President Trump and those of us in his national security team are re-establishing deterrence -- real deterrence ‒ against the Islamic Republic of Iran."

Shifting explanations

Trump administration officials have issued confusing explanations, contradicting each other about how imminent a threat the Iranian general posed, whether they had specific intelligence on the threat and even what that threat was, with Trump saying one thing, then another, while officials offered varying explanations.

Immediately after the strike, Pompeo told CNN Soleimani had been involved in planning an "imminent attack" in the region that put American lives at risk, adding that the US made an intelligence-based assessment that killing Soleimani would save Americans.

The Pentagon, however, offered a slightly different account, saying in a statement that the strike was carried out to deter future attacks against US interests.

While both could be true, the discrepancy has resulted in some confusion over how the administration intends to explain its reasoning for killing the man many considered to be the second most powerful figure in Iran without congressional approval.

During the question and answer portion of his remarks Monday, Pompeo did reiterate that "there was in fact a set of imminent attacks that were being plotted by Qasem Soleimani," but his emphasis on deterrence marked a notable departure from how he has sought to justify the strike in the 11 days since it took place.

Barr's comments also indicate the administration may be pivoting away from its core defense of the strike and reframing its argument around the idea of deterrence.

"Our ability to deter attacks had obviously broken down. The Iranians had been given a number of red lines and were crossing those lines," he said.

"This was a legitimate act of self-defense because it disrupted ongoing attacks that were being conducted, a campaign against the Americans. And it reestablished deterrence, it responded to attacks that had been already committed," Barr added. "Our purpose and our expectation was not to trigger a broader conflict or that events would spin out of control. On the contrary, we believed that the strike would restore deterrence and help avoid a upward spiral of the violence."

Rep. Justin Amash slammed the attorney general's comments, tweeting that the "red herring here is from Bill Barr."

"When there is a campaign that involves repeated attacks on American targets, then there is no excuse for the administration not to have sought an authorization from Congress, as the Constitution demands. Otherwise, imminence is required," the independent from Michigan added.

Comparing 'apples to oranges'

Critics argue that Barr's mischaracterized the Obama administration's position on drone strikes in an attempt to defend the Soleimani strike.

"Barr is comparing apples to oranges," according to CNN legal analyst Steve Vladeck.

"The Obama administration took the view that those strikes were authorized by Congress through the 2001 Authorization for the Use of Military Force, as opposed to the President's inherent constitutional authority as commander in chief. With those different authorities come different legal analysis," he said.

"The reason why imminence is viewed as such an essential part of the Article II question is because, without it, the President would arguably have the authority to use military force by himself in a remarkably broad array of situations," Vladeck added.

Details of the administration's legal argument remain unclear as the War Powers Resolution notification sent to Congress in the days after the operation remains classified.

But it broadly hinges on the same argument used by the Obama administration to conduct operations against ISIS -- a provision stating the President is authorized to use military force to defend the US against "the continuing threat posed by Iraq."

While many of the post-9/11 Office of Legal Counsel opinions related to presidential war powers have been withdrawn by previous administrations, there are still several that remain in force and could be cited by the administration to defend the strike against Soleimani.

One such opinion from 2002 explains the view of broad presidential authority to order military action without any additional legal authority.

"Article II vests in the President, as Chief Executive and Commander in Chief, the constitutional authority to use such military forces as are provided to him by Congress to engage in military hostilities to protect the national interest of the United States. The Constitution nowhere requires for the exercise of such authority the consent of Congress," it states.

US national security adviser Robert O'Brien also told reporters last week that the killing of Soleimani was "fully authorized" under the 2002 Authorization for Use of Military Force.

However, the administration has failed to convince congressional Democrats that the 2002 AUMF provided the legal authorization to conduct the strike.

'Totally consistent'

President Donald Trump's claim last week that Soleimani was targeting four embassies before he was killed, has only fueled more questions about the administration's rationale for carrying out the strike.

Defense Secretary Mark Esper on Sunday would not provide intelligence to back up Trump's comments but said he shared the President's belief that the embassies were threatened by Soleimani.

Esper also explicitly said on CBS that he had not seen any intelligence to back up Trump's claim about the four diplomatic outposts.

"I didn't see one with regard to four embassies," Esper said when asked if there was a specific piece of evidence.

O'Brien said "very reasonable security precautions" were taken, but suggested no specific warning was given to the embassy in Baghdad.

"We're not going to cut and run every time somebody threatens us," O'Brien said on Sunday when ABC asked why the Baghdad embassy was not evacuated. He emphasized military reinforcements which were moved to the region. "We are not going to have another Benghazi," he said, referring to a 2012 attack in Libya that left four Americans dead, including the US ambassador.

Pompeo has not said there were any threats to specific US embassies, describing the threat posed by Soleimani as one that "included attacks on US embassies."

Trump's claim was further undermined Monday after CNN reported State Department officials involved in US embassy security were not made aware of imminent threats to four specific US embassies.

Trump said Monday the intelligence that led to Soleimani's killing has been "totally consistent" but again declined to provide evidence supporting the claim.

"Well first of all, I think it's been totally consistent but here's what's consistent: We killed Soleimani, the number one terrorist in the world by every account. That person killed a lot of Americans, killed a lot of people. We killed him," Trump told reporters when asked specifically about the threat to the four US embassies.