A government monitoring body has cast serious doubts on Taiwan's ability to launch a credible all-volunteer military force, undermining a crucial plank in President Ma Ying-jeou's defense policy, and raising difficult questions about the island's ability to defend itself against a possible attack from China.

In a report unveiled Tuesday, the Control Yuan quoted high-ranking retired military officers, including a former navy commander, as saying that the defense ministry's failure to attract enough recruits to replace the existing conscription-based system spells bad news for Taiwan's military deterrent.

The all-volunteer transition was supposed to have been completed by 2015 but in September the defense ministry delayed implementation by two years amid continuing recruiting failures.

For the first 11 months of 2013, only 30 percent of the recruiting target was met.