 At 07 : 15 , Nagumo ordered his reserve planes to be re @-@ armed with contact @-@ fused general purpose bombs for use against land targets . This was a result of the attacks from Midway , as well as of the morning flight leader 's recommendation of a second strike . This had been under way for about 30 minutes when , at 07 : 40 , the delayed scout plane from Tone signaled that it had sighted a sizable American naval force to the east , but neglected to describe its composition . Later evidence suggests Nagumo did not receive the sighting report until 08 : 00 . 
