President Trump made the decision to directly target Qasem Soleimani within the last couple of days as specific intelligence came in that the Iranians had been working against US interests in the region, a senior administration official said.

"Soleimani was in the region to pull together those last strings to activate," the official said.  

A congressional source echoed that sentiment telling CNN there was credible intelligence on multiple attacks in the works by Iran's Islamic Revolution Guards Corps (IRGC) and Iraq affiliates but noted that this has been true at various points for a long time. This source did not say what specifically prompted the strike or elevated the immanency of the threat.

The planning process picked up momentum when Defense Secretary Mark Esper and Secretary of State Mike Pompeo flew to Mar-a-Lago on Sunday and presented Trump with intel about multiple threats and Soleimani’s movement – details that ultimately led to the decision to move forward with the strike, two sources told CNN.  

Prior to the strike, White House lawyers in consultation with national security officials put together a "strong rationale" the strike against Soleimani would not lead to war and that the President, as commander in chief, had the authority to not ask for congressional authorization over a matter of self defense, the administration official said. 

That legal rationale formed the basis for not going to Congress for authorization beforehand.

The administration official said kidnapping of US citizens was an ongoing concern but that was not the overarching concern that prompted the strike based on the latest intelligence.

"It was something we were concerned they might do, but not the only thing we were concerned about," the official said.

More on Trump's decision making process: Even though Trump made the decision over the last couple of days, the official said it wasn't a snap decision to launch the strike.

The US had been tracking the Iranian threat streams for several months but didn't respond because they held back on attacks against US citizens. The official would not specify what exactly the latest intelligence showed that ultimately prompted the strike, but it became clear that Soleimani was the ringleader of a specific and imminent threat against the US. The administration felt it was important to send a strong message to Iran that it needed to understand how serious the US was viewing its actions.