"We obviously have lots of options. We've developed a number of plans to deal with threats from North Korea. But the reality is that every one of those options does not provide, you know, what I would call acceptable risk at this point," Panetta said on MSNBC Sunday.

"So I think we need to have a good defense. We need to develop those options. But we need to use them frankly to push both China and North Korea to negotiations. I think ultimately that's the only way we're going to resolve this issue," he said.

Tillerson said the two decades of diplomatic efforts failed to disarm the North, and there was no point in pursuing the diplomatic path any longer. He also declared an end to former President Barack Obama's North Korea policy, known as "strategic patience," which centers on waiting for Pyongyang to show good faith while increasing sanctions and pressure on the regime. (Yonhap)