Foreign Minister Ban Ki-moon says he is unsure if the six-way nuclear talks will resume this month.

Returning from a two-week trip to the World Economic Forum, Europe and Africa, Ban said North Korea has yet to reply to his proposal to resume the talks this month.

On the North's counterfeiting, he said the United States is still considering what measures to take.

Ban also rejected calls for the revision of the mutual defense treaty with Washington as unnecessary, saying proponents are basing their conclusions on hypothetical situations.