By Yi Whan-woo

President Moon Jae-in said Thursday that North Korea is nearing a "red line" that he and U.S. President Donald Trump warned it not to cross amid Pyongyang's evolving missile threats.

Speaking in a live television news conference, Moon defined his own "red line" as "completing development of an intercontinental ballistic missile (ICBM), mounting a nuclear warhead on it and using it as a weapon."

"This is my idea of a red line and North Korea is increasingly approaching the threshold of that red line," the President told reporters at Cheong Wa Dae. "We must prevent any additional provocations at this stage. The international community must share our serious concerns and it's why the U.N. Security Council unanimously passed sanctions against North Korea recently."

Moon warned that North Korea may face harsher sanctions should it continue to make provocations.

"It will not be able to stand them eventually. And I warn Pyongyang not to take risks and make any further provocations," he said.

Moon previously asked North Korea not to violate his "red line" July 5 following its first ICBM test a day earlier. Pyongyang carried out its second ICBM test July 28.

"I do not know how we'll react if North Korea crosses the red line while refusing to respond with peaceful denuclearization of the Korean Peninsula as agreed to by South Korea and U.S.," Moon said back then.

In January, then-President-elect Trump drew what appeared to be a "red line" for North Korea: Testing a ballistic missile that could reach parts of the U.S. with a nuclear warhead.

He then tweeted that "It won't happen!"