Chief Cabinet Secretary Yoshihide Suga said the purpose of Abe's visit on December 26-27 was to console the souls of those who died in the war.

While the lack of an apology could disappoint some U.S. war veterans, Abe hopes the visit will showcase the tight alliance between the former foes. Experts say it is a message Abe wants to send both to regional rival China and to U.S. President-elect Donald Trump, who has criticized Tokyo as a free-rider on defense.

"This visit is for the sake of consoling the souls of those who died in the war, not for the sake of an apology," Suga told a news conference the day after Abe announced the visit.

"I think that the prime minister's visit will be an opportunity to send the message that the calamity of war must not be repeated and express the value of reconciliation between Japan and the United States," he said.

The visit to Hawaii with U.S. President Barack Obama could also boost Abe's popularity rating - already robust at around 60 percent - and raise the likelihood that he will call a snap election for parliament's lower house.

It will come seven months after Obama became the first serving U.S. president to visit the Japanese city of Hiroshima, where the United States dropped an atomic bomb in the closing days of the war in 1945.

"The planning for a Pearl Harbor visit has been in the works ever since Obama visited Hiroshima. It's mostly a reciprocal gesture and symbolic of the U.S. and Japan burying the hatchet," said Columbia University emeritus professor Gerry Curtis.

"It sends a message to China about the strength of the U.S.-Japan relationship (and is) probably also intended to send the same message to Trump," he said.

A boost in popularity ratings would give Abe a freer hand to call a snap election in January before opposition parties are ready. No election need be held until 2018 but speculation persists that Abe wants to call a vote sooner to minimize losses for his ruling bloc, which holds a two-thirds majority in the chamber.