An unwarranted assumption

A front-page piece in Wednesday's NYT discussing the possible consequences for U.S.-Japan relations of the Democratic Party of Japan's election victory (Mark Landler and Martin Fackler, "U.S. Is Seeing Policy Thorns in Japan Shift," NYT, 9/2/09, p.A1, continued p.A10) contains this passage:

"[Incoming P.M. Yukio] Hatoyama's views [as expressed in an excerpted article from a Japanese journal that appeared in English translation recently on the NYT website] sent many in Washington's diplomatic establishment scurrying to learn more about him and the Democrats. That highlighted a problem: While American officials and academics have spent decades cultivating close ties with the Liberal Democrats, who have governed Japan for most of the last half century, they have built few links to the opposition."

And whose fault is that? Surely it wasn't prudent to assume that the Liberal Democrats would be in power in Japan forever.