Pyongyang tested two of them in July

South Korea said on Monday it was talking to the United States about deploying aircraft carriers and strategic bombers to the Korean peninsula after signs North Korea might launch more missiles in the wake of its sixth and largest nuclear test. Officials said activity around missile launch sites suggested North Korea planned more missile tests.

“We have continued to see signs of possibly more ballistic missile launches. We also forecast North Korea could fire an intercontinental ballistic missile,” Jang Kyoung-soo, acting deputy minister of national defence policy, told a Parliament hearing on Monday.

North Korea tested two ICBMs in July that could fly about 10,000 km , putting many parts of the U.S. mainland within range and prompting a new round of tough international sanctions.

Joint exercises

South Korea’s Air Force and Army conducted exercises involving long-range air-to-surface and ballistic missiles on Monday following the North’s nuclear test on Sunday, its joint chiefs of staff said in a statement.

In addition to the drill, South Korea will cooperate with the United States and seek to deploy “strategic assets like aircraft carriers and strategic bombers”, Mr. Jang said. South Korea’s Defence Ministry also said it would deploy the four remaining launchers of a new U.S. missile defence system after the completion of an environmental assessment by the government.

The roll-out of the controversial Terminal High Altitude Area Defense (THAAD) system at a site south of the South Korean capital, Seoul, is vehemently opposed by neighbouring China and Russia, had been delayed since June.

Sunday’s test had registered with international seismic agencies as a man-made earthquake near a test site. Japanese and South Korean officials said the tremor was about 10 times more powerful than the one picked up after North Korea’s previous nuclear test a year ago.

Australian Prime Minister Malcolm Turnbull said that, while North Korea was not a puppet state of China, Beijing needed to do more to pressure its neighbour.