North Korea has fired three ballistic missiles into the waters off its east coast, say South Korean officials.
The missiles were launched from the Hwangju region, South Korea's Joint Chiefs of Staff (JCS) said on Monday, according to the Yonhap news agency.
There was no information on the types of missile fired or how far they flew.
North Korea is barred from testing nuclear or ballistic missile technology, but recent months have seen it carry out a string of missile tests.
It last fired a ballistic missile just two weeks ago from a submarine off its eastern coast, as South Korea and the US began annual military drills which routinely anger the North. On that occasion the KN-11 rocket that was fired flew for about 500km (300 miles) before falling into the Sea of Japan.
This latest test takes place as world leaders meet at the annual G20 economic summit, being hosted for the first time in China.
The August rocket launch was considered its most successful test of a submarine-launched ballistic missile. A test of mid-range missiles in June was also considered successful.
What is the Terminal High Altitude Area Defense System (THAAD)?
- Shoots down short- and medium-range ballistic missiles in the terminal phase of their flight
- Uses hit-to-kill technology - where kinetic energy destroys the incoming warhead
- Has a range of 200km and can reach an altitude of 150km
- US has previously deployed it in Guam and Hawaii as a measure against potential attacks from North Korea
1. The enemy launches a missile
2. The Thaad radar system detects the launch, which is relayed to command and control
3. Thaad command and control instructs the launch of an interceptor missile
4. The interceptor missile is fired at the enemy projectile
5. The enemy projectile is destroyed in the terminal phase of flight
The launcher trucks can hold up to eight interceptor missiles.