South Korea and the US held the “two-plus-two” meeting of their foreign and defense ministers on Thursday, where they exposed perception gaps on North Korea and China issues.

Their joint statement does not even contain the phrase, “denuclearization of North Korea,” not to mention “keeping China in check,” which is one of the cornerstones of US foreign policy.

For the South Korea-US alliance, North Korea’s nuclear weapons are the most urgent issue.

Pyongyang threatens Washington with its atomic bombs and intercontinental ballistic missiles to break down sanctions against the North and make the US withdraw its troops from South Korea.

North Korean leader Kim Jong-un has vowed to unify the Korean Peninsula by its nuclear force.

Despite this, the South Korea-US joint statement did not include the word, “denuclearization.” Instead, the statement said that North Korean nuclear and ballistic missile issues are a priority for the alliance, and it reaffirmed the shared commitment to address and resolve these issues.

While the North’s nuclear threats have become much more serious, the South and the US could not even agree on expressing “denuclearization” in their joint statement.

The leaders of Australia, India, Japan and the US -- the “Quad” -- included “the complete denuclearization of North Korea” in their joint statement after their recent summit.

The phrase was also included in the joint statement of the US-Japan Security Consultative Committee’s two-plus-two meeting involving their respective foreign and defense ministers on March 16.

Considering its inclusion in the Quad and US-Japan joint statements, it was likely excluded at the prompting of South Korea.

South Korea bears the brunt of the danger of North Korea’s nuclear weapons. Even if the US proposed to exclude the denuclearization of North Korea from the statement, it would be normal for Seoul to ask Washington to include it.

US State Secretary Antony Blinken mentioned the “denuclearization of North Korea” in a joint press conference, but South Korea’s Foreign Minister Chung Eui-yong said, “I believe that it is more correct to say that it is about the denuclearization of the Korean Peninsula.”

Chung added the denuclearization of the Korean Peninsula, a phrase that the South uses, means that South Korea has already been denuclearized and it is suggesting to North Korea that both Koreas should go along together.

Denuclearization of North Korea literally means the elimination of all of its nuclear weapons. Denuclearization of the Korean Peninsula means the removal of nuclear weapons not only in the North but also in the South if they ever exist. Pyongyang demands the denuclearization of the “Chosun Peninsula,” effectively the same expression as the Korean Peninsula. However, the phrase used by North Korea covers not only its own nuclear weapons, but also the removal of the US nuclear umbrella that protects South Korea and even the withdrawal of US forces from the South.

It is hard to understand why the effectively same expression as used by the North is more correct when it can make Pyongyang misinterpret it to its advantage.

Blinken said that “Beijing’s actions make forging a common approach among our allies all the more important at a time when we’re seeing a rollback of democracy and human rights around the world.”

He effectively urged South Korea to keep in step with the US in holding China in check.

But the word “China” was not included in the South Korea-US joint statement.

The Quad leaders are forming a joint front against China, but South Korea has remained aloof apparently to avoid piquing Beijing. Not only the Quad countries, but also the entire West is uniting against China’s pursuit of global hegemony.

If Seoul keeps up a passive stance on the efforts to check China, Washington will likely question if South Korea is an actual ally.

The perception gap between South Korea and the US is worrisome in that it can undermine their alliance, the cornerstone of South Korea’s security.

In order to boost its national interests amid an escalating confrontation between the US and China, it must try to close differences with the US and strengthen its alliance.

South Korea must keep in mind that it can protect its sovereignty from China’s authoritarian hegemony only when its alliance with the US is rock-solid. It must also remember that it is impossible to denuclearize North Korea without the US alliance.