CNN:

The attackers had rocket propelled grenades and machine guns, while the US troops were armed only with rifles and were in unarmored trucks according to officials. It had been considered 'unlikely' they would run into opposition and initial reports being reviewed indicate some locals in the area may have known an attack was planned, two officials said.

The failure to anticipate an attack and the fact there were no US rescue and recover assets close by meant nearly an hour went by before the evacuation of the two wounded and three dead US troops by French Super Puma helicopters could be completed.

Defense Secretary James Mattis said the rescue was timely stating: "I completely reject the idea that that was slow." But he did say an investigation will determine if changes are needed. "We will look at this and say was there something we have to adapt to now? Should we have been in a better stance."

One indication of how unexpected the attack was: the unit in Niger "had actually done 29 patrols without contact over the previous six months," Joint Staff Director Lt. Gen. Kenneth F. McKenzie Jr. told reporters.

Officials who have read the initial after-action reports say there was confusion and uncertainty on the ground after what was a completely unexpected attack. The team was particularly vulnerable because it was in two separate locations when the attack began. Some were walking back from a meeting with local villagers. Others were waiting outside, guarding the vehicles that the US troops were using.

While French helicopters were able to get the team to safety, the critical failure to find Johnson for another 48 hours has not been explained. His body was eventually found in a nearby area, but military investigators do not know why he was left behind during the French led evacuation and if he was alive even for a short period of time, US officials tell CNN.

Military officials have acknowledged that the incident is under investigation and that security procedures for teams operating in Africa are in the process of being reviewed. But it remains to be seen if Trump will choose to weigh in on the failings that led to the deadliest combat incident of his presidency so far.