By Phil Stewart and Kiyoshi Takenaka
TOKYO (Reuters) - U.S. President Donald Trump's defense secretary on Friday reaffirmed America's commitment to its mutual defense treaty with Japan during a meeting with Prime Minister Shinzo Abe in Tokyo.
Jim Mattis, who was on his first trip since taking over the Pentagon, appeared eager to reassure Japan of U.S. resolve, after an election campaign that saw Trump question the value of U.S. alliances.
Mattis said provocations from North Korea left no room for doubt about U.S. commitment, a similar message he delivered over the past two days in South Korea.
"I want to make certain that Article 5 of our mutual defense treaty is understood to be as real to us today as it was a year ago, five years ago - and as it will be a year, and 10 years, from now," Mattis said.
Article 5 obliges the United States to defend territories under Japanese administrative control.
Japan has been keen for assurances that Trump's administration would continue Washington's previous policy of committing to defend disputed East China Sea islands that are under Japanese control but claimed also by China.
Abe said he was convinced that, with Trump and Mattis, the United States and Japan could demonstrate to the world their "unwavering alliance."
Trump singled out both South Korea and Japan on the campaign trail, suggesting they were benefiting from the U.S. security umbrella without sharing enough of the costs.
Mattis is due to hold sit-down talks on Saturday with Defense Minister Tomomi Inada, who has repeatedly said Japan is bearing its fair share of the costs for U.S. troops stationed there and has stressed that the alliance is good for both nations.
Japan's defense spending remains around 1 percent of GDP, far behind China, which is locked in a dispute with Japan over the East China Sea islets, known as the Senkakus in Tokyo and the Diaoyus in Beijing.
(Reporting by Phil Stewart and Kiyoshi Takenaka; Editing by Clarence Fernandez)