On Jan. 19, 1960, the United States and Japan signed an agreement to firm up an alliance that has lasted half a century. The treaty, however, did more than this: over the course of the next 50 years, it was to lead to a number of complex negotiations between the two nations, be the source of much political wrangling and lead to the birth of the Japanese radical movement of the 1960s and the 1970s.

The treaty was signed just 13 years after the Japanese constitution was agreed upon by the government of Japan and the allied occupation forces led by General Douglas MacArthur at a time when many politicians in the Asian nation were questioning some of the articles.

The alliance has survived for half a century, however, despite controversies along the way, and on Tuesday, Prime Minister Yukio Hatoyama reaffirmed Japan's commitment to working with Washington.

"The U.S. military presence based on the Japanese-U.S. security treaty, I think, will continue to serve the public good by giving a great sense of security to the countries in the region," the prime minister said, calling the alliance "indispensable."

He added that he hoped to see ties between the nations deepen in the years to come.

Mistakes made?

In the five years before the treaty was signed in 1960, a new alliance had been formed at the top of Japanese politics -- the Liberal Democratic Party (LDP) -- a loose alliance of politicians from the center and right whose main purposes were to keep the socialists from power and to reassess the constitution.

In its initial years, the party hoped for a future in which there would no longer be foreign forces in Japan, and Article 9 of the constitution, which states "the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes," would be reformed. And Japan promised that "land, sea, and air forces, as well as other war potential, will never be maintained."

The first LDP Prime Minister Ichiro Hatoyama, the grandfather of the current prime minister, was a strong supporter of bringing about the revisions. Hatoyama was soon replaced by Nobosuke Kishi, however, who sought a compromise with the United States. The problem, as he saw it, was that while Japan was not allowed armed forces, it had no commitments of protection from its ally across the Atlantic.

After negotiations, Kishi signed with the United States a deal that stated, "The Parties, individually and in cooperation with each other, by means of continuous and effective self-help and mutual aid, will maintain and develop, subject to their constitutional provisions, their capacities to resist armed attack, " and also allowed the U.S. troops to stay on Japanese soil.