“Days, weeks,” Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, said on Friday, when asked how imminent any attacks could be, without offering more detail other than to say that new information about unspecified plotting was “clear and unambiguous.”

But some officials voiced private skepticism about the rationale for a strike on General Suleimani, who was responsible for the deaths of hundreds of American troops over the years. According to one United States official, the new intelligence indicated “a normal Monday in the Middle East” — Dec. 30 — and General Suleimani’s travels amounted to “business as usual.”

That official described the intelligence as thin and said that General Suleimani’s attack was not imminent because of communications the United States had between Iran’s supreme leader, Ayatollah Ali Khamenei, and General Suleimani showing that the ayatollah had not yet approved any plans by the general for an attack. The ayatollah, according to the communications, had asked General Suleimani to come to Tehran for further discussions at least a week before his death.