Japan could call on only Akagi, Kaga, and Soryu in February 1939. Hiryu would not commission until July and Zuiho until December 1940, while Shokaku and Zuikaku had not yet been launched. Some construction might be accelerated after war began, but those ships could not support the opening operations. Kido Butai did not yet exist as the later administrative organization or as its familiar mass of carriers. Japan could still attempt a carrier raid, though it would have fewer flight decks against a Singapore already placed on a war footing.
Notable Point · 1:05:00-1:07:24
What Japan's carrier force actually contained in February 1939
Only Akagi, Kaga, and Soryu were ready, so the concentrated carrier force familiar from 1941 did not yet exist in ships or organization.