system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How was it so easy for America to fly into Hiroshima and Nagasaki and drop those bombs without any opposition?

I'm watching a few documentaries on these events and tried looking up this answer. The pilots stated that they just flew over these cities, dropped the bombs and left without any resistance. How could Japan not see an unidentified airplane on a radar and pursue it?
gpt
At that point in the war, the Japanese navy and air force was pretty much destroyed, they had very little left in the form of air defense.  By August 1944, the Japanese navy was down to using kamikaze pilots that pretty much only knew how to take off, and sort of fly their plane. 

The bombings of Hiroshima and Nagasaki was a full year later, in August 1945. Japan had almost no naval or air defense, so even if they saw the bombers on the radar, all they could do is point at the screen and watch.