THAAD antimissile system South Korea
© U.S. Department of Defense / Reuters
The deployment of the THAAD antimissile system in South Korea, which China sees as a threat, may be followed by further steps, a senior US diplomat said. It comes as Washington pushes Beijing to put in place more sanctions against North Korea.

The US and South Korea announced in June a plan to deploy THAAD antimissiles by the end of 2017. China strongly objected to the move, saying it would compromise its own capabilities. Washington insists that the system would be aimed against threats from North Korea.

"Every single day that goes by, North Korea becomes a more and more acute threat to South Korea, Japan, countries in the region, and the US. And it gets closer to the day when it can actually put a nuclear weapon in an intercontinental ballistic missile that can reach the continental US. That's not acceptable for us," US Deputy Secretary of State Tony Blinken said during a lecture at Seoul National University.

"We have been very clear with China and others that we will have to continue to take defensive steps to protect ourselves and protect our allies and partners. And sometimes those kinds of steps we think that China does not like even though they are not directed at China. For example, the decision... to deploy the THAAD missile defenses system," he added as cited by Yonhap news agency.

Beijing has doubts over the justification for the deployment, saying Washington is using the pretext of the North Korean threat to deploy more military assets in the region to ensure its supremacy in the face of China's growing capabilities.

The statement from Blinken comes days after a senior Chinese official visited North Korea. Vice Foreign Minister Liu Zhenmin led a Chinese delegation to Pyongyang on Monday, becoming the first top-ranking official to visit China's awkward ally in eight months. The North Korean state media said the delegation came to discuss joint border issues.

North Korea relies on China in many aspects of its economy, from supplies of food, fuel and machinery to Beijing's turning a blind eye on Korean guest workers employed by Chinese firms. After Pyongyang's fourth nuclear test in January, the UN Security Council passed new, tougher economic sanctions.

China is in the best position to enforce them, but the US says Beijing is not doing enough. China also opposed imposing further sanctions after the fifth nuclear test in September, saying they apparently did not stop North Korea from developing nuclear weapons and missiles. The US vice secretary apparently suggested that further antimissile deployments may not be necessary if China goes along with the US sanctions bid.

"If we are able to build a sustained, comprehensive sanction regime with regard to the DPRK, it can succeed in forcing a choice on Kim Jong-un between continuing to pursue nuclear weapons and missiles or actually having an economy that answers basic needs for his people and ends North Korea's isolation," Blinken said.

"By far, the best way to do that is working cooperatively and hand-in-hand with China. And that is the purpose of our engagement now."

North Korea is developing nuclear and missile capability citing a military threat from the US and its Asian allies.