Typically International Business is not a standard function within business. Some standard functions are finance, customer service, product, research and development, marketing, sales and distribution. It is possible that large multinational corporations would have an international business function.
The four phases of strategic management are, roughly, assessing, strategic formulation, implementation of plans (sources, distributors, etc), and evaluation and redesign of plans.
International business funtion of this corporation would be important to the four stratgic phases in the first phase of assessing;; in the second phase of strategy formulation; in the third phase of implementation. Without gathering, considering, and implementing data from international business, the strategy would be incomplete.