Urgent diplomacy is needed on the Korean Peninsula. To address North Korea's nuclear weapons and ballistic missile programs, to be sure. But also for South Korea, where Seoul is embroiled in a bitter diplomatic spat with Tokyo that threatens to sap the U.S.-led alliance at a crucial time.

The fight is focused around so-called "history issues" — unresolved (or resolved, in Tokyo's view) grievances over Japan's brutal occupation of Korea from about 1910-1945. Novelist William Faulkner's famous reminder that "The past is never dead. It's not even past" seems to apply in Northeast Asia, where a trade dispute has developed over a South Korean Supreme Court ruling against two Japanese firms over forced labor during the war years.

Japan's government says that this issue was settled when the two nations re-established diplomatic relations in 1965. So, in a case of history impacting modern markers of industrial might, Tokyo put export controls on chemicals necessary for the South's semiconductor and smartphone industries.

Both sides have political wind in their sails.

Prime Minister Shinzo Abe, whose party won a decisive majority in Sunday's parliamentary elections, will soon become Japan's longest-serving prime minister. And in Seoul, South Korean political parties have shown rare resolve and unity: Liberals and conservatives have coalesced around the issue, which may boost President Moon Jae-in's party.

Other history issues, including "comfort women," or the forced prostitution of some South Korean women during the war, have not faded away in the decades after Japan's defeat in 1945.

But current conflicts may concentrate the minds of envoys.

On Tuesday, South Korean fighter jets fired 360 rounds of warning shots at Russian military aircraft, flying as part of a joint Russian-Chinese air patrol, that twice entered the country's airspace. Meanwhile, North Korean leader Kim Jong Un inspected a newly built submarine that could increase the range of its already formidable missiles. And on Wednesday North Korea fired two test projectiles off its coast. China's rise, which could be the biggest potential threat to regional peace, continues apace.

President Donald Trump dispatched National Security Adviser John Bolton to try to patch up the rift. But the threats, from emboldened adversaries and from quarreling allies alike, may make direct diplomacy necessary.