Ideally, seeking peaceful development and stability across the Taiwan Strait is in the interest of Taiwan's national security and in favor of social well-being. However, whether peace is achievable does not only depends on unilateral efforts from Taiwan, but rests on cooperation from both sides of the Taiwan Strait. Given the fact that the People's Republic of China has never renounced the use of forces against Taiwan, judging from the present situation across the Taiwan Strait, Taiwan would face a serious contradiction between its pursuits of national security, on the one hand, and peaceful coexistence with mainland China, on the other hand. The finding is that Taiwan will face defense dilemmas, including defense budget cut, strategy disorientation and problem of force deployment, if Taiwan considers resources allocation and defense cost with the goals of seeking Cross-Strait peace and economic development.