WASHINGTON (Kyodo) President Barack Obama on Tuesday urged a renewal and bolstering of the U.S.-Japan alliance as the two countries marked the 50th anniversary of the signing of the security treaty amid a rift over relocating the Futenma airfield.

"America's commitment to Japan's security is unshakable, and our cooperation to meet common challenges is a critical part of our engagement with the world," Obama said in a statement.

"And just as we honor the countless Americans and Japanese who have built the ties that bind our nations, we also look to the future with a determination to build upon the foundation of their progress," he said.