Japanese ships probably underway to New Guinea according to the U.S. Joint Intelligence Committee. Daily summary dated 28 April 1942

An item reported that were there indications that some Japanese surface vessels might be enroute to Rabaul [Papua New Guinea] coming from Truk (Japanese Mandates). While there was no task force available for a major offensive in Melanesia the occupation of Tulagi (Solomon Islands] was expected on short notice and possible followed by an attack on Por Moresby.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 139 dated 28 April 1942.