Cross-strait security is the most challenging issue faced by Taiwan Government. This issue widely affects all aspects of our national defense, diplomatic policy, economic and cultural development and exchange. However, this issue is also under strong international influence, namely the trilateral relation among U.S. China & Taiwan. Since 1996, there has been gradual yet fundamental change in this trilateral relation. The turning point comes when U.S. claims that its cross-strait policy is underpinned by so-called three pillars: One China, Cross-strait dialogue, and peaceful solution. Since then one China principle almost dominates all trilateral engagements. It is also observed that under this influence status-quo of cross-strait relationship i.e. no-independence (at Taiwan side) vs. no forceful unification (at China side) has become the basic policy thinking of three parties, at least the U.S. side.