Sea and the land-based air units carried out deceptive communications to indicate the carriers were training in the Kyushu area." The main Japanese naval bases (Yokosuka, Kure, and Sasebo) all engaged in considerable radio deception. Analysis of the bearings from Navy DF stations account for claimed breaks of radio silence, and when plotted, the bearings point to Japanese naval bases, not where the Kido Butai actually was. On 26 November, CAST reported all Japan's aircraft carriers were at their home bases. Rochefort, with Huckins and Williams, states there were no dummy messages used at any time throughout 1941 and no effort by the Japanese to use serious deception. When asked after the attack just how he knew where Akagi was, Rochefort (who commanded HYPO at the time) said he recognized her "same ham-fisted" radio operators. (The Japanese contend that radio operators were left behind as part of the deception operation.) The critical DF-tracked radio transmissions show bearings that could have not come from the strike force. Emissions monitored from CAST, or CAST's report Akagi was off Okinawa on 8 December 1941, are examples, though some transmissions continue to be debated. To deceive radio eavesdroppers, IJN Settsu commanded by Captain Chiaki Matsuda sailed from Taiwan to the Philippines simulating radio traffic for all six fleet carriers of the 1st Air Fleet and two other light carriers. U.S. contact with Japanese submarines Additionally, Japanese submarines were sighted and attacked (by the destroyer ) outside the harbor entrance a few hours before the attack commenced, and at least one was sunk—all before the planes began launching. This might have provided enough notice to disperse aircraft and fly off reconnaissance, except, yet again, reactions of the duty officers were tardy. It has been argued that failure to follow up on DF bearings saved . If she had been correctly directed, she might have run into the six-carrier Japanese strike force. After the attack, the search for the attack force was concentrated south of Pearl Harbor, continuing the confusion and ineffectiveness of the American response. Allied intelligence Locally, Naval Intelligence in Hawaii had been tapping telephones at the Japanese Consulate before the 7th. Among much routine traffic was overheard a most peculiar discussion of flowers in a call to Tokyo (the significance of which is still publicly opaque and which was discounted in Hawaii at the time), but the Navy's tap was discovered and removed