By localizing the production of core parts and intermediate goods previously imported from Japan, Korean firms have been striving to increase their market share and profit in the final goods market in which Japanese firms are dominating. Korean producers' efforts, however, have often been thwarted by Japanese suppliers' "strategic" behavior. This competitive strategy involves Japanese exporters supplying parts and intermediate goods at very high prices until Korean firms must locally develop them, and then setting the prices far below the previous level so that the profitability of localization is dramatically reduced, or even means a loss for the Korean manufacturer. This paper intends to explain the strategic behavior of Japanese firms through the concepts of strategic interactions and joint economies. Strategic interactions can be aggressive or accommodating depending on whether competitors are dealing with strategic substitutes or complements. Joint economies exist in multi-stage competition when competition in the previous state favorably influences "profits" of the ensuing stage. Competition between Korean and Japanese firms (a two-stage game involving production and technology rivalries) can be characterized by joint economies and strategic substitutes: joint economies since technological improvement results in more profits in the production stage; and strategic substitutes since an increase in marginal profits of one firm brings about a decrease in marginal profits of the other in a duopolistic production stage. This implies that the flood of "low price" Japanese substitutes is an almost "natural" phenomenon in the context of the duopolistic market described in this paper. In the technology competition stage, on the other hand, technology development and technology transfer can be either strategic complements or substitutes. This implies that, in typical comparative static analyses, the effect of changes in exogenous variables cannot be expected a priori. Thus it becomes very difficult to determine the desirability of applying various policy measures such as countervailing duties, R&D subsidies, and creating demand for localized products. For these reasons, it is indeed likely that the measures suggested as means of circumventing the strategic behavior of Japanese firms (and enhancing technological development of Korean firms) may not work.