CANBERRA, Australia—Australia will accelerate construction of a fleet of warships as part of an ambitious buildup meant to more closely integrate its military with the U.S. and respond to instability in Asia.

Prime Minister Tony Abbott on Tuesday said his conservative government would start work on a 20 billion Australia dollar (US$14.6 billion) fleet of nine advanced frigates within five years—three years earlier than expected—while also beginning construction of 20 large offshore combat vessels.

“This is about ensuring that we have a strong surface fleet to deal with whatever naval contingencies we face indefinitely,” Mr. Abbott told reporters. “This is a message of hope and confidence to the people of our country.”

A strategic blueprint to be released as soon as next month lays out a modernized fleet of 40 surface warships and submarines that will allow Canberra to take a larger security role—as called for by the U.S.—in the face of unease over China’s rise and island-building in the South China Sea.

Allies like Britain, Canada and the U.S., as well as European counterparts like Germany and the Netherlands, have been restraining defense budgets in response to sluggish economic conditions. But Mr. Abbott, buoyed by a decadelong resource boom that helped contain debt, has pledged to boost military spending to 2% of GDP from the current 1.8%, adding A$3.5 billion a year to the current A$32 billion military budget.