Australia to speed missile defence development, THAAD not appropriate: Turnbull

It is a ground-based missile defence system that works against short, medium and intermediate-range ballistic missiles at the terminal stage of flight.

U.S. President Donald Trump Thursday also called the DPRK's launch of its first intercontinental ballistic missile on Tuesday a "shame" that has to be stopped, during his meeting with South Korean and Japanese leaders in Germany on the sidelines of the G20 Summit.

The Australian government is bolstering its weaponry and military forces in response in part to the "growing threat posed by ballistic and cruise missile capability" and their proliferation in the Indo-Pacific and Middle East regions, the Department of Defence said in a 2016 report.

THAAD batteries are also installed in Guam and Hawaii to stop an intermediate-range missile from North Korea.

South Korea's Yonhap news agency said the long-range heavy bombers flew close to the tense and heavily militarised land border with the North before turning back. "The focus is on protecting our forces both at sea and on the ground-our deployed forces in the field". The test takes on greater significance after North Korea launched an intercontinental ballistic missile earlier this week.

Still, in recent testimony to Congress, Vice Admiral James Syring, then the director of the Missile Defense Agency, said FTT-18 would aim to demonstrate THAAD's ability to intercept a separating IRBM target.

While China and North Korea have continuously opposed the deployment of THAAD, there have been concerns from South Korea as well with regards to the anti-missile system.

THAAD is a ground-based missile defense system created to shoot down short-, medium- and intermediate-range ballistic missiles.