The United States and Japan on Tuesday vowed to build an unshakable alliance to deal with their common challenges for the 21st century and to promote mutual cooperation and security.

"The ministers commit themselves to further building an unshakable U.S.-Japan alliance to adapt to the evolving environment of the 21st century," said the U.S.-Japan Security Consultative Committee in a joint statement marking the 50th anniversary of the signing of the U.S.-Japan security treaty.

The committee consists of Secretary of State Hillary Rodham Clinton, Secretary of Defense Robert Gates and their Japanese counterparts Foreign Minister Katsuya Okada, Defense Minister Toshimi Kitazawa.

On Jan. 19, 1960, the two countries signed the Treaty of Mutual Cooperation and Security, under which both parties assumed an obligation to assist each other in case of armed attack on territories under Japan administration.

Also under the treaty, the United States could currently maintain about 50,000 troops in Japan, half of whom are stationed in Okinawa.

According to the committee, the two countries recommit themselves to internationally-recognized standards of human rights, the purposes and principles of the Charter of the United Nations, and to the objectives of the treaty.

The committee said the two countries will continue to strengthen their ability to respond to "contingencies" that could threaten their common strategic objectives in the Asia-Pacific region, namely to ensure the security of Japan and to maintain peace and stability in the region.

The joint statement was issued at a time when difference remains between Washington and Tokyo over the relocation of a U.S. Marine Corps base in Okinawa.

Since coming to power in September 2009, Prime Minister Yukio Hatoyama and his Democratic Party of Japan have said the Japanese government would like to see the relationship with the United States to become "more equal", and views reassessing the Status of Forces Agreement (SOFA) as one means of achieving the equal relationship.

According to the SOFA agreement signed by Japan's former governing Liberal Democratic Party (LDP) and the Bush administration in 2006, 8,000 U.S. troops will be relocated from Okinawa Prefecture to Guam, and a base in the urban center of Futenma will be moved to a more rural area.

The Obama administration has been calling on the Hatoyama-led government to implement the SOFA and to relocate the base.