Many factors influence Taiwan's security: geography, international trends and the attitude of the international community toward the Taiwan issue, ROC political and economic conditions, relations across the Taiwan Strait, U.S.-PRC-ROC relations, the intentions of PRC leaders, the military capabilities of the PLA, and the capabilities and intentions of the United States to intervene on Taiwan's behalf. Together, these form Taiwan's security environment, the circumstances within which Taipei must formulate its strategy for deterring and, if need be, for winning a war in the Taiwan Strait.