Most of Unocal's energy reserves are located in Asia, so the notion that the company is somehow an "American" corporation is a little shaky to begin with. In addition, the Supreme Court's recent decision in the Kelo case renders any of their U.S. assets potentially worthless anyway -- since these assets could be taken from them in exchange for a "fair market value" that CNOOC has no control over.
In what country did Unocal incorporate? From which country does Unocal receive the tax benefits of incorporation?