(This January 21 story corrects name of EU speaker in 15th paragraph to Anne Kemppainen after she was misidentified by United Nations as Croatian ambassador Vesna Batistic Kos)
By Stephanie Nebehay
GENEVA (Reuters) - North Korea said on Tuesday it was no longer bound by commitments to halt nuclear and missile testing, blaming the United States' failure to meet a year-end deadline for nuclear talks and "brutal and inhumane" U.S. sanctions.
North Korean leader Kim Jong Un set an end-December deadline for denuclearisation talks with the United States and White House national security adviser Robert O'Brien said at the time the United States had opened channels of communication.
O'Brien said then he hoped Kim would follow through on denuclearisation commitments he made at summits with U.S. President Donald Trump.
Ju Yong Chol, a counsellor at North Korea's mission to the U.N. in Geneva, said that over the past two years, his country had halted nuclear tests and test firing of inter-continental ballistic missiles "in order to build confidence with the United States".
But the United States had responded by conducting dozens of joint military exercises with South Korea on the divided peninsula and by imposing sanctions, he said.
"As it became clear now that the U.S. remains unchanged in its ambition to block the development of the DPRK and stifle its political system, we found no reason to be unilaterally bound any longer by the commitment that the other party fails to honour," Ju told the U.N.-backed Conference on Disarmament.
Speaking as the envoy from the Democratic People's Republic of Korea (DPRK), North Korea's official name, Ju accused the United States of applying "the most brutal and inhumane sanctions".
"If the U.S. persists in such hostile policy towards the DPRK there will never be the denuclearisation of the Korean peninsula," he said.
"If the United States tries to enforce unilateral demands and persists in imposing sanctions, North Korea may be compelled to seek a new path."
U.S. military commanders said any new path could include the testing of a long-range missile, which North Korea has suspended since 2017, along with nuclear warhead tests.
"DO THE RIGHT THING"
U.S. disarmament ambassador Robert Wood voiced concern at Pyongyang's remarks and said Washington hoped the North would return to the negotiating table.
"What we hope is that they will do the right thing and come back to the table and try to work out an arrangement where by we can fulfil that pledge that was made by President Trump and Chairman Kim to denuclearise," he said.
South Korean Ambassador Jang-keun Lee said there must be substantial progress in denuclearisation to "maintain and build upon the hard-won momentum for dialogue".
"Therefore, early resumption of negotiations between the United States and the DPRK is critical," he said.
Anne Kemppainen, head of the European Union's disarmament section, also called on North Korea to stick to the talks.
Pyongyang, slapped with multiple Security Council resolutions and sanctions, has rejected unilateral disarmament and given no indication that it is willing to go beyond statements of broad support for the concept of universal denuclearisation.
North Korea has said in previous, failed talks that it could consider giving up its arsenal if the United States provided security guarantees by removing its troops from South Korea and withdrew its so-called nuclear umbrella of deterrence from South Korea and Japan.
Impoverished North Korea and the rich, democratic South are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty.
The North regularly used to threaten to destroy the South's main ally, the United States, before rapprochement began after the 2018 Winter Olympics in South Korea.
(Reporting by Stephanie Nebehay; Editing by Jon Boyle and Nick Macfie)