President Donald Trump on Friday accused North Korea of "behaving very badly" and "playing" the US for years, shortly after Secretary of State Rex Tillerson hinted that military options were on the table.
"China has done little to help!" Trump also said in a tweet from his personal account.
Tillerson, on a visit to South Korea, is due to visit Beijing on Saturday and meet Chinese President Xi Jinping.
After meeting with South Korean Foreign Minister Yun Byung-se on Friday, Tillerson told reporters that the US "policy of strategic patience has ended".
"We are exploring a new range of diplomatic, security and economic measures. All options are on the table," he said during a joint news conference in Seoul.
While the US does not want military conflict, if North Korea elevates the threat of its weapons program to a level Washington believes requires action, "that option's on the table," Tillerson added.
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North Korea has tested four ballistic missiles last week, and vowed "merciless ultra-precision strikes from ground, air, sea and underwater" if the US and South Korea violate its "sovereignty and dignity even a bit".
--IANS
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