The Cabinet approval last month of the 25-trillion yen medium-term defense buildup program came without heated debate among lawmakers or the public, to the apparent surprise of some Defense Agency officials.

"I thought (the program) was kind of 'challenging,' " a senior agency official said on condition of anonymity after the program was approved, suggesting the ruling coalition's smooth acceptance of the agency's plan was rather unexpected.

Although there was some political tug of war within the ruling block on the proposed introduction of aerial tankers, lawmakers widely showed little interest in the huge spending package, proposed in mid-December.