SEOUL (Reuters) -- North Korean leader Kim Jong Un said the breakdown in talks with the United States has raised the risks of reviving tensions, and he is only interested in meeting President Donald Trump again if the United States comes with the right attitude, state media KCNA said on Saturday.

Kim said that he will wait "till the end of this year" for the United States to decide to be more flexible, according to KCNA.

"It is essential for the U.S. to quit its current calculation method and approach us with new one," Kim said in a speech to the Supreme People's Assembly on Friday, KCNA said.

Trump and Kim have met twice, in Hanoi in February and Singapore in June, building goodwill but failing to agree on a deal to lift sanctions in exchange for North Korea abandoning its nuclear and missile programs.

Trump said on Thursday he is open to meeting Kim again, but in his speech on Friday, the North Korean leader said the outcome in Hanoi led him to question the strategy he embraced last year of international engagement and talks with the United States.

The Hanoi summit "aroused a strong question if we were right in taking the steps with strategic decision and bold resolution, and evoked vigilance as to the U.S. true willingness to improve its relations with the DPRK," Kim said, using the initials of North Korea's full name, the Democratic People's Republic of Korea.

In Hanoi, the United States came "to the talks only racking its brain to find ways that are absolutely impracticable" and did "not really ready itself to sit with us face-to-face and settle the problem," Kim said.

"If it (the United States) keeps thinking that way, it will never be able to move the DPRK even a knuckle nor gain any interests no matter how many times it may sit for talks with the DPRK." he said.

"We will wait for a bold decision from the U.S. with patience till the end of this year but I think it will definitely be difficult to get such a good opportunity as the previous summit," Kim added.

Kim's comments signal he won't cling to talks with the United States forever, said Kim Dong-yup of Kyungnam University's Institute for Far Eastern Studies in South Korea.

"That probably indicates that the North is triggering plans to diversify its diplomatic relations with other countries," he said.

THIRD SUMMIT IN DOUBT

Kim said that his personal relationship with Trump is still good, but that he had no interest in a third summit if it were a repeat of Hanoi.

At a meeting with South Korean President Moon in Washington on Thursday, Trump expressed a willingness for a third summit with Kim but said that Washington would leave sanctions in place on Pyongyang.

Kim said the United States "is further escalating the hostility to us with each passing day despite its suggestion for settling the issue through dialogue." The current U.S. policy of sanctions and pressure is "as foolish and dangerous an act as trying to put out fire with oil," he added.

Still, Kim said he would not hesitate to sign an agreement if it takes into account both countries' considerations.

The United States had continued to provoke North Korea by testing an anti-ballistic missile system and conducting military drills with South Korea despite Trump's announcement that large-scale exercises would end, he said.

Last month, a senior North Korean official warned that Kim might rethink a moratorium on missile launches and nuclear tests in place since 2017 unless Washington makes concessions such as easing sanctions.

South Korea's Blue House said in a statement that officials would "do what we can in order to maintain the current momentum for dialogue and help negotiations between the U.S. and North Korea resume at an early date."

Kim complained that Washington is coercing South Korea into abiding by sanctions and not pushing forward with inter-Korea projects.

North Korea has a choice "to keep maintaining the atmosphere of improving the North-South ties or to go back to the past when the ties plunged into a catastrophe with the danger of a war increasing," he said.

Still, North Korea is committed to better North-South relations and peaceful unification, Kim said.

"I make it clear once again that it is my unwavering determination to turn the North-South ties into those of durable and lasting reconciliation and cooperation by holding hands with the south Korean authorities and to write a new history of the nation, peaceful and co-prosperous," he said.