President Trump sent his regards late Monday to the Emperor of Japan ahead of his abdication from the throne, acknowledging the “close relationship” that the U.S. has with Japan over the last thirty years.

“On behalf of the American people, the First Lady and I offer our heartfelt appreciation to Their Majesties the Emperor Akihito and Empress Michiko,” Trump wrote in a statement. “As the Heisei era draws to a close and a new generation prepares to ascend the throne, I want to recognize the tremendous importance that the United States attaches to its close relationship with Japan.

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Trump credited the U.S.’ partnership with Japan as helping navigate the global challenges of the last 30 years, adding: “We look forward to continuing the tradition of partnership and cooperation with Japan, our great ally, in the new era,” Trump said.

Emperor Akihito, 85, who has held the title since 1989, is the first Japanese monarch in more than 200 years to voluntarily abdicate the throne. Akihito began his abdication rituals at a Shinto shrine Tuesday morning as Japan embraces the end of his reign with reminiscence and hope for a new era.

Television images showed Akihito in a traditional robe entering the main Shrine of Kashikodokoro for a shrine ritual that partially was released to the public. In a palace ceremony later in the day, Akihito will announce his retirement before other members of the royal family and top government officials.

His reign runs through midnight when his son Crown Prince Naruhito becomes new emperor and his era begins. Naruhito will ascend the Chrysanthemum throne Wednesday. In a separate ceremony, he will inherit the Imperial regalia of sword and jewel, as well as Imperial seals as proof of his succession as the nation's 126th emperor in the world's oldest hereditary monarchy from the 5th century.

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Akihito devoted his career to making amends for a war fought in his father's name while bringing the aloof monarchy closer to the people. With his commoner-born wife, Empress Michiko, he reached out to the people, especially those who faced handicaps and discrimination, as well as those hit by disasters, illuminating the hardships of people often overlooked by society.

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Akihito's efforts won him widespread respect, and recent media surveys have shown public support for the imperial family at 80 percent, the highest ever for the institution.

The Associated Press contributed to this report.