After covering the landings on Tulagi on 3 May, "Shōhō" headed north to cover the invasion convoy the next day and was not present when aircraft from the American carrier attacked Japanese shipping at Tulagi. This air strike confirmed that at least one American carrier was in the vicinity, but the Japanese had no idea of its location. They launched a number of reconnaissance aircraft the following day to search for the Americans, but without result. One Kawanishi H6K "Mavis" flying boat spotted "Yorktown", but was shot down by one of "Yorktown"s Grumman F4F Wildcat fighters before she could radio a report. US Army Air Forces (USAAF) aircraft spotted "Shōhō" southwest of Bougainville Island on 5 May, but she was too far north to be attacked by the American carriers, which were refueling. That day, Rear Admiral Frank Jack Fletcher received Magic intelligence that placed the three Japanese carriers known to be involved in Operation MO near Bougainville, and predicted 10 May as the date of the invasion. It also predicted airstrikes by the Japanese carriers in support of the invasion several days before 10 May. Based on this information, Fletcher planned to complete refuelling his ships on 6 May and move closer to the eastern tip of New Guinea to be in a position to locate and attack Japanese forces on 7 May.