The Japanese war planes were seen on radar, well in advance of the attack… when they sent the message up the chain of command… they were told…
“Don’t worry about it”
Some theorize that the US Government wanted to get into WW2… this was their ticket to get public support for it.
The problem was the complete opposite, the radar contacts were NOT “run up the chain of command”, they ended up in a waste basket at the first link in the chain. I’m not sure who the “some” are who theorize that the US wanted to get into WWII, but had that been true there were numerous opportunities long before 1941. In reality, the US was trying to avoid going to war, almost a point that was delusional.
At 7:02 AM on 7 December, the radar station at a radar site in northern Ohau spotted a formation of airplanes. Despite the fact that the Hawaiian Islands were supposed to be under a heightened state of alert for signs of a Japanese attack, what transpired was a tragic chain of bungling and errors.
The radar site called Fort Shafter’s Intercept Center to report the contacts and request a radar plot. The experienced plotters who probably would have taken the report seriously were, tragically, all out to breakfast at the time.
The infamous “Don’t worry about it,” came from the only one left in plotting at the Intercept center, an inexperienced Lieutenant Kermit Tyler, who was just into his second day on the job.
Tyler dismissed the radar contacts that were reported by the radar station as likely being a flight of B-17s coming in from California even though there were far too many contacts for this to be likely.
There were a host of other errors and delays that further prevented the reports from being verified and being passed on to sound the alarm. It makes for fascinating reading and there are many accounts of this incident. The bottom line is that the radar report went no further up the chain of command until it was too late.
Multiple investigations and inquiries document the chain of events on December 7. A Naval Court of Inquiry conducted some years later cleared Lieutenant Tyler of responsibility for the incident citing a host of factors including his inexperience and lack of training. No disciplinary action was ever taken against him. It has always struck me as strange, but Tyler continued to serve in the US Air Force after the war and was promoted several times, he retired, I believe it was in the 1960s.
Numerous books give excellent accounts of the events leading up to this tragic day. I’ve never understood why some feel the need to turn Dec 7 into some kind of wild conspiracy theory, the truth is tragic enough.
once you look down in the water and see the Arizona… knowing there are hundreds of bodies in it still… you will never forget Pearl Harbor. 
