TOKYO: Japan "can't move ahead" with a costly US missile defence system, Prime Minister Shinzo Abe said Tuesday, throwing his support behind a decision to suspend deployment of the controversial programme.

In a surprise announcement a day earlier, Japan's Defence Minister Taro Kono said the deployment of the Aegis Ashore system would be suspended, citing cost and time constraints.

Abe's comments appear to suggest the system, which was originally estimated to cost Japan $4.2 billion over three decades, may be scrapped altogether. The government had originally guaranteed that interceptor missile gear would not land in residential areas near where the system was based. But Kono said his ministry concluded that maintaining that promise would require a costly and time-consuming hardware upgrade.

"Since the premise we explained to local people has changed, we can't move ahead further. That's our decision," Abe told reporters on Tuesday.

But he said the government was committed to considering alternatives. "There should not be a gap in our country's defences. We want to hold discussions on the necessary measures."

The Aegis Ashore radar purchase, approved in 2017, was seen both as part of attempts by Tokyo to bolster its defensive capabilities after North Korean missile launches, and as a way to foster closer ties with Washington.-AFP