A spokesperson for the U.S. State Department says that diplomatic channels between Washington and Pyongyang "won’t be open forever."

A tweet by U.S. State Department spokeswoman Heather Nauert did suggest, however, there may be a chance for dialogue on North Korea's nuclear weapons for the time being.

Nauert also warned that North Korea will not obtain nuclear capability, stressing it is up to Pyongyang whether force or diplomacy will ensure that.

After a meeting with Chinese President Xi Jinping on Saturday, U.S. State Secretary Rex Tillerson said the U.S. has kept open “a couple of direct channels” with the North, denying it is in a dark situation or a blackout.

However, U.S. President Donald Trump said in his tweet on Sunday that he told Tillerson that “he is wasting his time trying to negotiate with Little Rocket Man,” referring to North Korean leader Kim Jong-un.

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