U.S. Defense Secretary Ash Carter said he thinks about the situation on the Korean Peninsula "every single day" as "a very large war" could break out there at any time.

"The DMZ on the Korean Peninsula is a place where we have to be ready to fight tonight. Every single day I think about our posture on the Korean Peninsula," Carter said on CNBC's "Squawk Box" over the weekend, referring to the Demilitarized Zone separating the two Koreas.

"It's something that we have to watch every single day," he said.

Carter said the United States and South Korea maintain narrow communications with North Korea across the DMZ in order to avoid accidentally coming into conflict that he said "would be a very large war that we would wage with our allies in South Korea."

"We would win; I have no doubt about it, but it's a very unpleasant war to have to wage, so we'd like to avoid it if we can.

And the only way to do that is to have some form of communication," he said.

Carter also said the biggest worry about North Korea is its nuclear program.

"There are talks in which we do participate, and not the Defense Department, but Secretary Kerry does of the so-called six party talks, which are China and Russia and South Korea and Japan and the United States and North Korea," he said. "They haven't gotten anywhere yet, but you can keep hoping that they will."

Meanwhile, Carter told the World Economic Forum in the Swiss ski resort of Davos that the U.S. military has played a key role in maintaining peace and stability in Asia.

"I'll just say one thing about Asia -- it's terribly important for this audience, because it's a big business market. It's half of the world's economy, half of its population. For 70 years, peace and stability have been kept in Asia, because of the American military. We aim to keep that going," he said.

Carter also noted that an invitation for North Korea to the World Economic Forum has been canceled because of the country's nuclear test.

"I know you had an invitation to the North Koreans, which by taking the self-isolating step, which seems to be their habit of testing a nuclear weapon, they're not here," he said. (Yonhap)