 Nagumo was now in a quandary . Rear Admiral Tamon Yamaguchi , leading Carrier Division 2 ( Hiryū and Sōryū ) , recommended that Nagumo strike immediately with the forces at hand : 18 Aichi D3A1 dive bombers each on Sōryū and Hiryū , and half the ready cover patrol aircraft . Nagumo 's opportunity to hit the American ships was now limited by the imminent return of his Midway strike force . The returning strike force needed to land promptly or it would have to ditch into the sea . Because of the constant flight deck activity associated with combat air patrol operations during the preceding hour , the Japanese never had an opportunity to position ( " spot " ) their reserve planes on the flight deck for launch . 
