National defense, that is, national defense, refers to military and military-related political, diplomatic, economic, cultural and other aspects of construction and struggle to defend national sovereignty and territorial integrity and guard against foreign aggression and subversion. The ancients regarded etiquette as a force to safeguard social and national security, which must be strictly observed and prevented from overstepping, and it was called national defense. Today, it refers to all measures taken to defend the sovereignty, territorial integrity and security of the country and prevent foreign armed aggression against the China People's Liberation Army's national defense service stamp and subversion. It means that national defense comes into being with the establishment of the country and serves the national interests. Churchill famously said, "We have no eternal friends or enemies, only eternal interests." This statement is in the language. National defense is directly related to national security, national dignity and social development. 1, the subject of national defense: the state. 2. Purpose of national defense: to defend national sovereignty, unity, national security and territorial integrity. 3. Means of national defense: military, political, economic and diplomatic. 4. The object of national defense: aggression and armed subversion. An important country cannot stand without defense, and the people cannot stand without defense. As a country and a nation, the most important thing is nothing more than two major events, one is development and the other is security. National defense is the product of human social development and security needs. It is a fundamental plan related to the life and death of the country and the nation. Modern national defense is also called social national defense, great national defense and national defense, including armed construction, national defense system, military science and technology, national defense equipment and industry, national defense engineering, military transportation and communication, manpower mobilization, national defense education and national defense laws and regulations. This is a huge and complicated system. From the supreme head of state to every citizen, from military to politics, economy, culture, education, science and technology and ideology are closely related to it. Modern national defense takes military forces as the core, including related non-military forces; It attaches importance to the war potential of the country, especially the mobilization efficiency in wartime; This is also Tian Li's comprehensive competition based on economy and technology. The modern army is an armed group with intensive knowledge and technology, and it emphasizes quality over "sea tactics". The role of national defense in peacetime is deterrence, which requires winning without fighting; The duty of national defense in wartime is actual combat, and the goal is victory. Role: (1) National security. (2) the premise of national independence. (3) An important condition for national prosperity and development. Four types of extensions. In order to safeguard their global interests, big countries pursue hegemonism, invade, subvert and infiltrate other countries. Defense equipment self-defense type. We should rely mainly on our own strength to win extensive international support, prevent foreign enemies from invading and safeguard our own security. China adheres to the national defense policy of peace and independence, and will never expand, nor will it allow other countries to invade an inch of our land. Alliance type. In the form of alliance, unite with other countries to make up for their own strength. It can be divided into expansion and self-defense, and it can also be divided into monistic and pluralistic alliances. The former has a big country as the leader. Neutral type. Small and medium-sized developed countries strictly abide by the peaceful and neutral battlefield defense policy and formulate an overall defense strategy and a defense system including soldiers and people. For example, Switzerland. China belongs to active self-defense. The international situation has gradually eased and hegemonism and power politics are still rampant. In peacetime, China should not only accelerate its development, but also ensure its security. "The wealth of nations" and "the theory of military strength" are the two pillars of China's standing among the nations in the world. Basic characteristics Modern national defense is the embodiment of a country's comprehensive national strength. The comprehensive national strength of a country includes: national strength, national potential, and the ability to turn potential into strength. It is an important symbol of a country's comprehensive national strength to make full use of various conditions and capabilities in national defense equipment and effectively transform them into national defense strength as soon as possible. Modern national defense is the competition of various forms of struggle, and military struggle is still the basic form. At the same time, political, economic, scientific and technological, diplomatic and other non-military struggles have intensified and played an increasingly important role. Modern national defense is not only a national act, but also an international act. The national behavior of national defense is mainly manifested in: the state uses various conditions and capabilities to build national defense; Relying on a strong national defense, the government can concentrate on formulating policies, mobilize all forces to develop the economy, and ensure that the country is prosperous and the people live and work in peace. The internationalization of national defense is mainly manifested in the following aspects: domestic and foreign countries, and national defense and international relations are closer; World peace and war, international economic prosperity and recession, all directly affect the country and national defense construction; The international and surrounding situation is turbulent, and the country must pay more attention to national defense. Once threatened or invaded by foreign countries, it must mobilize national defense forces to meet external challenges. Modern national defense has multi-level goals. The lowest goal is self-defense. The scope of national defense is limited to national territory and territorial waters, with a view to safeguarding national sovereignty and territorial integrity. The intermediate goal is a regional goal, limited to the limited surrounding areas outside the national territory, focusing on increasing the depth and flexibility of national defense and creating a more relaxed surrounding environment for national security and development. The highest level goal is the global goal, and national defense covers the whole world, focusing on protecting the country's interests in the world. The enlightenment given is 1. Strong national defense is the basic condition for the survival and development of a country and a nation. 2. Correctly handling the relationship between national defense construction and economic construction is an important prerequisite for building a strong national defense; 3. Science and technology are the fundamental driving force for building a strong national defense; 4. The people are the source of strength for building a strong national defense; Upholding the leadership of the Party and building a modern revolutionary army loyal to the Party and the people is the fundamental guarantee for building a strong national defense. 6. Economic development is the foundation of a strong national defense. 7. Political prosperity is the foundation of national defense consolidation. 8. National unity and national unity are the keys to a strong national defense.