A profound transformation is under way in world military security picture at the beginning of the new century. 1) A qualitative leap is taking place in the military clout of some countries to varying degrees along with worldwide rebound in military spending. 2) The connotation and denotation of strategic deterrent are in the process of a deep-going changeover as military strategy and operational policy of the major military powers are undergoing remarkable readjustments, adding a more extensive dimension to the concept of strategic deterrent. 3) Network and outer space are standing out as new arenas for international military competition, resulting in a shift to a five-dimensional warfare in the real sense of the term, with the United States leading the way. The negative repercussions of such developments could not be underestimated for the 21st century international security map as an entity. New military confrontation and tensions among big powers may result from heightened unnecessary animosity among some countries due to armament expansion, notably the development and deployment of certain sophisticated weapons systems. Imbalances in world balance of military strength will worsen as the gap in military muscles widens between the developed and developing nations in the wake of the quicken pace of upgrading in weaponry. This new round of transformations on the world’s military front will pose new pressures to China’s stability and advances. The ever-mounting China-related factors in the readjustments in military strategy of Washington and Tokyo may turn Beijing into their imaginary latent opponent in military competition. But in the final analysis, military security will be conditioned by the broader world trends and subject to the restraints of economic, political and diplomatic and many other factors. So long as peace and development remain to be the major strategic pursuits of nations, some negative transformations would not lead to new large-scale conflicts and/or wars. A profound transformation is under way in world military security picture at the beginning of the new century. 1) A qualitative leap is taking place in the military clout of some countries to varying degree along with worldwide rebound in military spending. 2) The connotation and denotation of strategic deterrent are in the process of a deep-going changeover as military strategy and operational policy of the major military powers are under remarkable readjustments, adding a more extensive dimension to the concept of strategic deterrent. 3) Network and outer space are standing out as new arenas for international military competition, resulting in a shift to a five-dimensional warfare in the real sense of the term, with the United States leading the way. The negative repercussions of such developments could not be underestimated for the 21st century international security map as an entity. New military confrontation and tensions among big powers may result from heightened un necessary animosity in some countries due to armament expansion, notably the development and deployment of certain sophisticated weapons systems. Imbalances in world balance of military strength will worsen as the gap in military muscles widens between the developed and developing nations in the wake of the quicken pace of upgrading in weaponry. This new round of transformations on the world’s military front will pose new pressures to China’s stability and advances. The ever-mounting China-related factors in the readjustments in military strategy of Washington and Tokyo may turn Beijing into their imaginary latent But in the final analysis, military security will be conditioned by the broader world trends and subject to the restraints of economic, political and diplomatic and many other factors. So long as peace and development remain to be the major match competingits of nations, some negative transformations would not lead to new large-scale conflicts and / or wars.