The U.S. and Japan have a close alliance. Ironically, this alliance is in many ways the product of the bloody rivalry between the two during World War II and which culminated in the Americans dropping the first nuclear bomb - the most destructive weapon in human history.

But the American occupation and reconstruction of Japan under the command of Gen. Douglas MacArthur brought the two country's close together. In 1951, the two countries signed a security treaty and expanded it with the 1960 Treaty of Mutual Cooperation and Security between the United States and Japan.

It's a close strategic partnership that's remained strong for six decades. Next month, the two country's militaries will team up for Exercise Yama Sakura 69, the 34th iteration of this U.S.-Japan exercise which began in 1982.

This year it will occur at Camp Itami in Osaka, Japan.  It's a U.S. Army Pacific (USARPAC) event, a simulation-driven joint command post exercise with U.S. the Army's I Corps and the Japanese Ground Self Defense Forces (JGSDF) Middle Army as the player units. Yama Sakura rotates each year to one of the five (5) JGSDF regional armies.

The exercise will bring together thousands of servicemembers with approximately 2,000 U.S. troops and 4,000 members of the JGSDF. Air and naval forces will also be on hand to allow for joint planning.

There will be 518 I Corps soldiers in Japan for Yama Sakura and 615 active and Reserve soldiers will participate at Joint Base Lewis- McChord Mission Training Complex.

Other American units participating in the massive exercise will be the 25th Infantry Division, 34th Infantry Division, 593rd Expeditionary Sustainment Command, 17th Fires Brigade, 65th Fires Brigade, 164th Air Defense Artillery Brigade, 201st Expeditionary Military Intelligence Brigade, 16th Combat Aviation Brigade, 555th Engineer Brigade, 364th Civil Affairs Brigade, 8th Theater Sustainment Command, 3rd Marine Expeditionary Brigade, the U.S. Navy's 7th Fleet and U.S. 5th Air Force.

The opening ceremony for Yama Sakura 69 will be Dec. 5 and the exercise will kick off the next day and run until Dec. 11.

Japan's post-WWII government has historically taken a near pacifist approach to foreign policy, only allowing Japanese forces to act in self-defense and prohibits offensive action abroad. But in recent years, the Japanese government has tested the constitutional limits on force.

JGSDF troops deployed to southern Iraq as part of the U.S.-led coalition after the 2003 invasion, though strict rules meant they couldn't use their weapons and required security escorts from Australian troops who could. Japanese engineers have also deployed as members of U.N. Peacekeeping missions; Japanese troops currently operate in war ravaged South Sudan.

In September, Japanese Prime Minister Shinzo Abe's government passed legislation to reinterpret pacifist clause of Japan's constitution. This came after a long round Japanese and Chinese officials clashing over territorial rights in the South China Sea, as well as ISIL's execution of two Japanese hostages in Syria this year.

Japan is a key ally as the U.S. military re-emphasizes East Asia as part of President Barrack Obama's "Pivot to the Pacific." The Obama administration has been in a showdown with Chinese President Xi Jinpeng over Chinese Naval activity in the South China Sea and the Pentagon has been strengthening ties with countries in the Pacific region - even former rivals such as Vietnam.

I Corps and JBLM have both been central to the Pacific Pivot, this year holding simultaneous joint exercises with Indian and Japanese troops in Washington state during the month of September. This month, JBLM even hosted Chinese troops for a humanitarian exercise.

Though the Pacific Pivot in many ways challenges China, neither side seems to want a violent confrontation.