Using the so-called “New York channel”, US negotiator with North Korea Joseph Yun has been in contact with diplomats at Pyongyang’s United Nations mission, the official said.
The New York channel is one of the few means the United States has for communicating with North Korea.
But, the rogue nation has made it clear it has little interest in serious talks before it develops a nuclear-tipped missile capable of hitting the continental US.
The last high-level contact between Mr Yun and North Korea was when he travelled to the hermit kingdom in June to secure the release of US student Otto Warmbier, who died shortly after he returned home in a coma.
The Trump administration has demanded North Korea release three other US citizens: missionary Kim Dong Chul and academics Tony Kim and Kim Hak Song.
Warmbier’s death was a factor in the chilling of US-North Korean contacts around that time but the biggest impact came from Pyongyang’s stepped-up testing, the official said.
The official added: “The preferred endpoint is not a war but some kind of diplomatic settlement.
“Diplomacy has a lot more room to go.”
But Trump‘s threats against North Korea are believed to have complicated diplomatic efforts.
It comes as tensions between the US and North Korea have escalated after Trump and Kim Jong-un have been engaged in a war of words which have sparked fears of military conflict.
US Secretary of State Rex Tillerson said on October 17 he would continue “diplomatic efforts… until the first bomb drops”.
His comments are a sign the US is directly discussing issues beyond the release of American prisoners, despite Trump having dismissed direct talks as pointless.
But, there is no sign that the discussions have improved relationships between the two nations, especially after the North conducting a series of nuclear tests.
Mr Yun told North Korean negotiators to “stop testing” nuclear bombs and missiles, the official said.
North Korea this year conducted its sixth and most powerful nuclear detonation and has test-fired a volley of missiles, including intercontinental ballistic missiles (ICBMs).
There is speculation as to whether the ICBMs have the capacity to reach the mainland US, but experts believe it could be only months until they are perfected.
The possibility that Pyongyang may be closer to attaching a nuclear warhead to an ICBM has alarmed the Trump administration, which in April unveiled a policy of “maximum pressure and engagement” that has failed to deter North Korea.
At the start of Trump’s presidency, Mr Yun’s instructions were limited to seeking the release of US prisoners.
The State Department official, said: “It is now a broader mandate than that”.
But he did not say whether authority had been given to discuss North Korea’s nuclear and missile program.
NATO chief Jens Stoltenberg has urged all United Nations members to fully and transparently implement sanctions against North Korea, which he said has emerged as a global threat.
Speaking at the UN on September 19, Trump called Kim Jong-un “rocket man” and vowed to “totally destroy” North Korea if it threatened the United States or its allies.
Twelve days later Trump said on Twitter his chief diplomat is “wasting his time trying to negotiate with Little Rocket Man”.
Democratic US senators introduced a bill on Tuesday to prevent Trump from launching a nuclear first strike on North Korea on his own.
It comes days before Trump’s first presidential trip to Asia.
A high-ranking North Korean defector said he backed the Trump administration’s policy of pressuring Pyongyang through sanctions, coupled with “maximum engagement” with the leadership and increased efforts to get information into North Korea to educate its people.
Thae Yong Ho was chief of mission at Pyongyang’s embassy in London until he defected in 2016.
Speaking to the Centre for Strategic and International Studies, he said: “I strongly believe in the use of soft power before taking any military actions.”