Since Japan has taken a major step toward defending other countries, nations in Southeast Asia are paying attention to the move as a potential way to rein in China's recent muscle-flexing.

However, there are limits to what Japan's troops can do in Asia, experts say.

"It is an era where a country can no longer defend itself on its own," Prime Minister Shinzo Abe told a news conference after his Cabinet approved bills on Thursday to drastically change Japan's exclusively defense-oriented security policy.