SEOUL - Secretary of State Rex Tillerson warned Friday that military action against North Korea is "an option on the table," an indication that President Trump has lost patience with failed diplomacy and is prepared to confront North Korea’s nuclear threat more aggressively.

Tillerson made the comments during a news conference in Seoul after visiting the tense buffer zone between rivals North and South Korea, the world’s most heavily armed border. He said that the "policy of strategic patience has ended" and that the United States was considering a range of measures aimed at persuading North Korea to abandon its nuclear ambitions: military, diplomatic and economic.

"Certainly we do not want to, for things to get to military conflict," Tillerson said: "(But if North Korea) elevates the threat of their weapons program to a level that we believe requires action, then, that option's on the table."

Tillerson is on a tour this week of China, Japan and South Korea. He vowed Thursday to take a "different approach" to North Korea after saying that 20 years of "diplomatic and other efforts" had failed to dissuade Pyongyang from developing its nuclear program. Previous U.S. administrations have held the threat of military action over North Korea in response to nuclear tests or missile launches. Tillerson's remarks go much further in stating that using the military is a real possibility.

"North Korea must understand that the only path to a secure, economic propitious future is to abandon its development of nuclear weapons, ballistic missiles and other weapons of mass destruction," Tillerson said. He called on China, one of the reclusive communist nation's only allies, to refrain from economic retaliations against South Korea for deploying an advanced U.S. missile defense system — known as THAAD — on its soil because of threats from Pyongyang.

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Beijing has curbed travel to South Korea and is targeting its companies on mainland China with restrictions because of the missile system. The State Department has described Tillerson's trip to Asia as a "listening tour" and a key part of that is listening to China. Tillerson will meet with President Xi Jinping in Beijing this weekend.

The demilitarized zone between North and South Korea that Tillerson visited Friday was created as a buffer zone between the two countries after the Korean War armistice was signed in 1953. It is guarded on both sides with land mines, razor wire fence, tank traps and hundreds of thousands of combat-ready troops.

Nuclear tests by North Korea

  • September 2016: Fifth, and possibly biggest, nuclear test carried out
  • January 2016: Experts skeptical over North Korea claims it carried out fourth nuclear test, of a hydrogen bomb
  • February 2013: New United Nations sanctions after third nuclear test staged, the first under new leader Kim Jong Un
  • May 2009: Second nuclear test, also underground
  • October 2006: First nuclear test conducted at an underground facility. United Nations imposes broad array of sanctions