The United States diplomatic channels with North Korea are not “open forever,” says the US State Department.
Spokeswoman Heather Nauert warned North Korean leader Kim Jong-un Sunday that the US may close the channels.
"Diplomatic channels are open for #KimJongUn for now. They won't be open forever," she tweeted.
Nauert further asserted that Pyongyang should forget about gaining a nuclear capability.
"#DPRK will not obtain a nuclear capability. Whether through diplomacy or force is up to the regime @StateDept," she said.
On Saturday, Secretary of State Rex Tillerson announced that Washington was maintaining direct diplomatic channels with the government in Pyongyang.
US President Donald Trump has said that Tillerson is “wasting his time” by negotiating with North Korea.
"I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man," the president tweeted Sunday. "Save your energy Rex, we'll do what has to be done!"
He later said "Being nice to Rocket Man hasn't worked in 25 years, why would it work now?” adding that "Clinton failed, Bush failed, and Obama failed. I won't fail."
Tensions between Washington and Pyongyang escalated last month, when Trump said on the floor of the United Nations that he would destroy North Korea over its nuclear activities.
Trump’s threats at the UN did not go down well with traditional US allies like the UK, France and Germany, which have all called for diplomatic solutions while supporting more economic sanctions.