As January progressed, Allied reconnaissance and radio traffic analysis noted the buildup of ships and aircraft at Truk, Rabaul, and the Shortland Islands.
Sepanjang bulan Januari, pengintaian dan analisis lalu lintas radio Sekutu mencatat adanya konsentrasi kapal-kapal dan pesawat terbang di Truk, Rabaul, dan Kepulauan Shortland.