The weapon to which he was referring is a ballistic missile known as the Rodong-1 (or "Worker"), capable of carrying both conventional and nuclear warheads. From the east coast of North Korea to the west coast of Japan is considerably less than 1,000 km (625 miles).
Mr Ikeda declined to reveal the origin of the "reports" but a similar one appeared last week in the Sankei Shimbun, the most anti-ommunist of Japan's daily newspapers. If true, they would not be a great surprise: the Institute of International Strategic Studies in London predicted last October that the Rodong-1 would be deployed in late 1996 or early 1997. Why then highlight the rumours now?
The fact is that, in the last few weeks, Tokyo's moderate diplomacy has changed dramatically. On the question of North Korea, Japan has been transformed from a cautious follower of the consensus, whose main concern was to avoid offending either South Korea or the United States, to the most hawkish of the countries directly concerned with the peninsula's fate.
The new policy has become most obvious in Japan's attitude towards food aid for North Korea. After two years of floods, the government in Pyongyang cannot feed its own people. After the first crop failure in 1995, Japan was one of the first to offer food. But now, in response to predictions of imminent famine, while the South has promised $6m (pounds 3.75m) of rice and the United States $10m, Japan is refusing to consider further aid.
The official reason is a story in itself. Earlier this year, information received from a North Korean defector appeared to confirm what was suspected for years: that spies from Pyongyang during the Seventies kidnapped more than a dozen Japanese, including a girl of 13, to serve as teachers of Japanese to trainee spies.
Others look for the answer in the realignment of conservative forces between the governing Liberal Democrats and the opposition New Frontier Party. But the most likely explanation lies far to the south in Okinawa, where 29,000 US servicemen are stationed. Since a young girl was gang raped by three US servicemen in 1995, Tokyo has come under intense pressure from Okinawans to send the Americans home. In persuading its own people to accept the continuing American presence, a missile-lobbing, childnapping near-neighbour is rather a useful tool - it is surely this which lies behind Japan's new hawkishness.