Japan and the United States on Friday lauded the decades-old security treaty that is the bedrock of their alliance, but which U.S. President Donald Trump has criticized as "unfair" and imbalanced.

The comments from the two countries' top diplomatic officials marked the 60th anniversary of the current treaty, which was first signed in 1951 and revised in 1960 under Prime Minister Shinzo Abe's grandfather, then-leader Nobusuke Kishi.

"While honoring the achievements of the past 60 years, we reiterate our unshakeable commitment to strengthen the Alliance and to uphold our common values and principles towards the future," said a joint statement by Foreign Minister Toshimitsu Motegi, Defense Minister Taro Kono, U.S. Secretary of State Mike Pompeo and U.S. Defense Secretary Mark Esper.