Nagumo was now unsure of what to do. Rear Admiral Tamon Yamaguchi recommended that Nagumo strike with the forces at hand: 18 Aichi D3A dive bombers each on "Sōryū" and "Hiryū", and half the cover patrol aircraft. Nagumo's opportunity to hit the American ships, however, was now limited. The Midway strike force would be returning shortly and needed to land or crash into the sea. Because of the constant flight deck activity, the Japanese did not get their reserve planes on the flight deck for launch. The few aircraft that were ready were defensive Fighter aircraft. Launching aircraft would have required at least 30 to 45 minutes. By launching right away, Nagumo would be using some of his reserve without proper anti-ship weapons. He had just seen how easily unescorted American bombers had been shot down. Poor discipline caused many of the Japanese bombers to get rid of their bombs and attempt to fight intercepting F4Fs. Japanese carrier rules preferred full strikes, and since Nagumo did not know the American force included a carrier, his response followed Japanese rules. In addition, the arrival of another American air strike at 07:53 made Nagumo want to attack the island again. Nagumo decided to wait for his first strike force to land, then launch the reserve, which would by then be armed and ready.