I am wondering if B17s ever flew bombing raids against the Japanese mainland, and if so, did they do it before the capture of Okinawa, which was much closer than the previously captured islands like Iwo Jima.
Some links indicating that only B29s were used.
Iwo Jima - Tokyo (one way): 760 miles/1220 km
Coastal China/Korea to Japan distance is on the order of 800km, but Japan held most, if not all, of the Chinese/Korean coast during the war.
B17-G range - Range: 2,000 mi (3,219 km, 1,738 nmi) with 6,000 lb (2,700 kg) bombload
B29 range - Range: 3,250 mi (5,230 km, 2,820 nmi)
Motivation for this question is a question Why was the USA planning on attacking Japan before Japan's attack on Pearl Harbour? concerning a claim by Chomsky asked on SE Politics that Japan had good reasons to start the war because it was feeling threatened by B-17 bombers.
Furthermore the title of the question implies not only the Japanese perception, but actual US intentions. Which I don't think is based on any kind of objective reality as the B-17 just lacked the range to bomb Japan from any area under US control (or outside the reach of Japan) in 1941.