U.S. National Security Adviser John Bolton said that North Korean leader Kim Jong-un wasn't prepared to accept U.S. President Donald Trump's "big deal" at their summit in Hanoi last week. 

Bolton said in an interview with Fox News on Sunday that Trump handed Kim two papers, one written in English and the other in Korean, presenting a deal in which the North will entirely denuclearize in return for an enormous economic future. 

However, Kim reportedly was not ready to take the deal. 

In a separate interview with CBS, Bolton said that he does not consider the summit a failure. He said he considers it a success defined as the president protecting and advancing American national interests. 

Bolton said there is no expiration date for talks on denuclearization, adding that President Trump is fully prepared to keep negotiating at lower levels or to speak with Kim again when it's appropriate.