SEOUL – North Korea’s test-firing today of a missile is a challenge not only to South Korea but also America, with the aim to see how — or even whether — President Biden will respond.

It appears to be no coincidence that this is taking place amid the war in Ukraine. The communist regime in Pyongyang had recently been respecting Communist China’s request that it hold off testing missiles during the Beijing Olympics. 

So far this year, the North Korean strongman, Kim Jong-un, has ordered eight test shots, including the latest launched today. The chances are that Mr. Biden will say nothing about the missile shot while worrying about what’s happening in Ukraine, in which he’s relying on sanctions that are unlikely to stop Russia’s invasion of a country that’s essentially helpless without foreign aid.

America has yet to decide how much aid and assistance it will give the beleaguered Ukrainian forces. Ukraine has made it clear that it needs arms and materiel and even advisers on the ground helping Ukrainian forces to use such weaponry. Instead, America and its NATO allies are, in the main, leaving the Ukrainians to fend for themselves against a Russian assault that includes tanks and air strikes.

The guarded nature of America’s response raises questions about how or even whether Mr. Biden would spring to the defense of South Korea if the North Koreans, with the support of the Communist Chinese and Russians, were to decide that the time was ripe to stage the Second Korean War.

Korea is not Ukraine. The Americans fought a terrible war on behalf of the South Koreans after the North Korean onslaught in June 1950, and the U.S. is still bound to South Korea by a longstanding defense treaty under which 28,500 U.S. troops remain in the South.

The alliance would appear quite strong, but the response of China and now North Korea to the Russian invasion of Ukraine shows the relationship between North Korea and the two great powers that prevented the defeat of the North in the Korean War.

The Chinese support the Russians, and a North Korean commentary accuses America of pursuing only “global hegemony and military supremacy in disregard of the legitimate demand of Russia for its security.”

The commentary, posted on the website of the North Korean foreign ministry, was North Korea’s first reaction to the invasion. It placed North Korea firmly on Russia’s side while justifying the need for nuclear warheads and missiles for security against America. 

With little more than a week to go before South Korea’s presidential election, North Korea is eager to influence the outcome. The message is clear.

The candidate of the ruling Minjoo or Democratic Party, Lee Jae-myung, advocating a policy of appeasement and reconciliation, would be expected to respond to North Korean missile tests with pleas for dialogue and understanding while urging the U.S. to soften its policies, ease up on sanctions, and go for an end-of-war declaration that would lead to a peace treaty in place of the armistice that ended the Korean War in July 1953.

North Korea’s missile and nuclear strength is obviously a deep point of pride under the Kim dynasty that has ruled the North since the Soviet Union installed Kim Il-sung, a former officer in the Soviet army, in Pyongyang after the Japanese surrender and the division of the Korean peninsula in August 1945.

There’s no way, of course, that Kim Il-sung’s grandson. Kim Jong-un, is going to give up his nuclear bombs and missiles, but the candidate of the opposition People Power Party, Yoon Suk-yeol, supports the Americans in demanding denuclearization as a prerequisite for a deal with the North.

Mr. Yoon has called for “rebuilding” relations with Washington, strained by disagreement between Washington and Seoul over the end-of-war declaration.

The North Korean commentary skillfully played on the sanction issue, saying “the root cause of the Ukrainian crisis lies in American ‘high-handedness and arbitrariness’” and blaming Washington for clinging to “the unilateral sanction and pressure.”

The American position is that North Korea has to be willing to talk over everything, including denuclearization. The North, insisting that, as a prerequisite for talks, Washington drop sanctions, has yet to respond to repeated U.S. calls to negotiate without “preconditions.”

President Moon’s government, meanwhile, appears highly uncertain as to what to do. Seoul may go along with sanctions, but Mr. Moon does not refer to Vladimir Putin by name or talk about democratic values or human rights while deploring the invasion.

Rather, Mr. Moon appears wary of offending China, the South’s largest trading partner and protector of North Korea, as well as Russia, from which South Korea imports 20 percent of its natural gas.