Secretary of State Rex Tillerson said the door is closing for diplomatic options against North Korea, but open for military action against the rogue nation, whose goal seems to be building a missile that can reach the US mainland.

“Let me be very clear,” Tillerson said during a news conference in Seoul, South Korea, “the policy of strategic patience has ended.”

However, after saying that, Tillerson said all options are on the table. “We’re exploring a new range of diplomatic, security and economic measures,” and while the US did not want to take military action, he said threats would be met with “an appropriate response.”

Trump later turned to his favorite social media outlet to let off steam. “North Korea is behaving very badly,” he stated, “they have been playing the United States for years. China has done little to help.”

South Korean Foreign Minister Yun Byung-se seemed to support the suggestion of military options against the North, according to the Washington Post.

“We have various policy methods available,” Yun said, “If imposing diplomatic pressure is a building, military deterrence would be one of the pillars of this building. We plan to have all relevant nations work together more closely than in the past and make sure that North Korea, feeling pain for its wrongdoings, changes its strategy.”

North Korea has artillery units aimed at South Korean metropolitan areas, where more than 20 million people reside just south of the demilitarized zone that separate North from South Korea. However, as North Korea continues to threaten its neighbors, military options may be the only way to deal with that threat.

Some lawmakers in South Korea are seeking a return of tactical nuclear weapons, especially if the North is successful in constructing an intercontinental ballistic missile.

Tillerson said the landscape must be reshaped in the area before diplomatic talks could be considered. Tillerson is visiting Beijing  Saturday to seek more pressure from them on South Korea.