The top diplomats and defense chiefs from the United States and Japan are meeting Thursday in Tokyo to review and strengthen security ties.
U.S. Secretary of State John Kerry said the leaders hope to lay out the U.S.-Japan security relationship for the region for the next 15 or 20 years.
"This alliance, which we believe is the linchpin alliance for the United States in the region, has not been updated since 1997 and as you said in your opening comments, a great deal has changed in this period of time."
The U.S.-Japan Security Consultative Committee is expected to cover regional security issues such as the North Korean nuclear program and Tokyo's maritime disputes with China.
The so-called "2+2" talks involve Kerry and U.S. Defense Secretary Chuck Hagel, as well as Japan's Foreign Minister Fumio Kishida and Defense Minister Itsunori Onodera.
Following a morning meeting between Hagel and Onodera, the Pentagon chief said the U.S.-Japan alliance must change in order to respond to new threats.
"We have new challenges, new threats, that we need to deal with, and that is always requiring review of obligations and alliances. With two partners like Japan and the US, we have been able to always adjust and always find the right way forward, as we deal with these new 21st-century threats."
Kerry and Hagel are in the middle of a multi-day tour across Asia that U.S. officials have described as an effort to advance President Barack Obama's new diplomatic and security focus on the Pacific.
Ahead of the talks, a senior State Department official said a "central pillar" of the White House rebalance toward Asia is strengthening ties with U.S. allies, noting that Japan is at the "top of the list."
Following the Tokyo meeting, Kerry and Hagel head to the Indonesian island of Bali on Friday for a ministerial meeting of the Asia-Pacific Economic Cooperation (APEC) forum, which Washington sees as a premier forum for boosting regional trade and investment.
President Obama is also scheduled to attend the APEC meeting, as well as a meeting next week of the Association of Southeast Asian Nations (ASEAN).
But those plans appeared to be in question, after President Obama on Wednesday cancelled the last two legs of his Asia trip to Malaysia and the Philippines in order to deal with the U.S. federal government shutdown.
A White House statement says Kerry will instead lead the U.S. delegation to each country. It said Mr. Obama reaffirmed the close partnership and alliance the U.S. has with Malaysia and the Philippines and committed to travel to both countries later in his term.