National defense is an important factor in a country's overall national strength. The stronger a country's military strength, the less likely it is to be violated by other countries. From this. ['A country with a strong national defense force must also have a strong overall national strength.', 'To improve the overall national strength, we must attach importance to the building of national defense forces.', 'Countries with strong military forces like to invade other countries.', 'National defense construction is the main direction of national construction.']