Top Iranian commander Qassem Soleimani was plotting to attack American military, diplomatic and financial targets in Syria and Lebanon, and comprised the imminent threat used to justify Soleimani's killing, according to NBC News, citing multiple US officials.

"When we start seeing extensive and very solid intelligence that [Soleimani] is plotting imminent attacks against the United States, the president as commander in chief has a duty to take decisive action," said a senior State Department official, adding "If we had not taken this action, and hundreds of Americans were dead, you would be asking me why didn't you take out Soleimani when you have the chance."

Gen. Mark Milley, chairman of the Joint Chiefs, said he is confident Soleimani was actively planning attacks against the U.S. in the Middle East and those attacks were imminent. "We had clear, compelling, unambiguous intelligence to indicate Qassem Soleimani was planning, coordinating, and directing a significant campaign of violence against the United States in the coming days," said Gen. Milley. -NBC News

Soleimani's targets are said to include US military outposts in eastern Syria, and diplomatic and financial targets in Lebanon. According to Gen. Milley, the US is confident that the "size, scale and scope" of the planned attacks constituted an imminent threat.

"By the way, it still might happen," he added.

A Syrian boy looks at a U.S. convoy patrolling near the Turkish border on Oct. 31, 2019. (Delil Souleiman / AFP)

Should Lebanon come under attack, the 173rd Airborne Brigade Combat team is on alert and prepared to deploy, should they come under attack. The deployment would consist of somewhere between 130 and 750 total troops.

A senior U.S. official said Soleimani had traveled to Syria, Lebanon and then to Iraq Thursday, and U.S. intelligence officials believe he was approving final plans for attacks in each location. Milley said Soleimani had been directing attacks against the U.S. inside Iraq, including a Dec. 27 attack near Kirtkuk that killed an American contractor and wounded four U.S. service members. "He approved it," said Milley. "I know that. One hundred percent." -NBC News

According to a senior Congressional aide briefed on the intelligence, however, lawmakers saw nothing linking Soleimani to an imminent attack - rather, what they saw was "exactly the sort of planning and coordination he has been doing for years," according to NBC. The aide added that while nobody doubts Soleimani was a threat to the United States, the case for acting on an imminent threat was not made.

Sen. Mark Warner (D-VA), ranking member of the Senate Intelligence Committe, said "I have real questions and want to get a full briefing from the intelligence community about the decision on this time and place."