This book is the result of a national research project led by Major General, Professor Dr. Nguyen Ba Duong. The content of the book includes 2 main parts. Part 1: Strategic adjustment of powerful countries. Part 2: Issues for the current defense of the Socialist Republic of Vietnam. The content of the book focuses on analyzing and clarifying the basics of powerful countries, identifying and pointing out the powerful countries in the contemporary world and their strategic adjustments affecting Vietnam. analysis, pointing out the cause of these strategic adjustments in the current period, especially of countries such as China, Russia, the United States, Japan and India. Thereby, pointing out the beneficial and detrimental effects on the peace, security and sustainable development of Vietnam.