United States have not yet received any response from North Korea regarding the meeting between two leaders.
South Korea who is mediating the talks said it has not received a response from Pyongyang on a summit between North Korean leader Kim Jong-un and US President Donald Trump.
South Korean officials said Mr Kim was prepared to give up his nuclear weapons.
"We have not seen nor received an official response from the North Korean regime regarding the North Korea-US summit," a spokesman for the South Korean Ministry of Unification said on Monday.
"I feel they're approaching this matter with caution and they need time to organise their stance."
Analysts are sceptical about what can be achieved through talks given the complexity of the issues involved.
Details on the planned talks remain vague, with no agreement yet on the location or agenda.
In a surprise development, Mr Trump on Friday accepted North Korea's invitation to direct talks.