Our nation's security priorities, and our military, are in transition. In the Middle East, we ended the war in Iraq and are reducing ground troops in Afghanistan with the shift of security responsibilities to Kabul. At home we are reassessing our military's size and composition as we seek to align our spending with our resources. And around the world we face a range of new security challenges, from continued upheaval in the Arab world to the imperative of sustaining our leadership in the Asia-Pacific. These challenges place a premium on the flexibility and small ground footprint of naval forces, which are being deployed longer and more often to advance our nation's interests.
The Department of Defense's January 2012 strategic guidance, Sustaining U.S. Global Leadership - Priorities for 21st Century Defense, addressed this new environment and our security priorities in it. Overall, the strategy focuses on important regions and current readiness and agility, while accepting reduced capacity and level of effort in less critical missions. In particular, the strategy directed that our military rebalance toward the Asia-Pacific while continuing to support our partners in the Middle East. Naval forces will be at the heart of both efforts.
After two decades of ground conflict in the Middle East, our security concerns and ability to project power in the region both center on the sea. U.S. ground forces continue to draw down in Afghanistan and around the region, so our commanders increasingly rely on naval aircraft to support and protect troops. Meanwhile, Iranian leaders speak provocatively about impacting maritime traffic throughout the Arabian Gulf. In response, we turned to maritime forces, doubling our minesweeping forces in the Gulf and deploying an additional carrier strike group to the region.
The focus of our rebalance, the Asia-Pacific, is fundamentally a maritime region. Our friends there depend on the sea for their food and energy, while more than 90 percent of trade by volume makes its way through the region over the water. Maritime security for Pacific nations is a matter of economic survival. Militarily, the vast maritime distances in the region make access via the sea essential to deterring and defeating aggression. Our fleet deployed in the Asia-Pacific will exploit the mobility of being at sea to project power against aggressors and avoid attacks, while their reinforcements and supplies will arrive via the ocean from the United States or regional bases.
The importance of the Asia-Pacific, and the Navy's attention to it, is not new. Five of our seven treaty allies are in the region, as well as six of the world's top 20 economies. We have maintained an active and robust presence in the Asia-Pacific for more than 70 years and built deep and enduring relationships with allies and partners there. While we remain present and engaged in the Middle East to address today's challenges, the Navy will build on its longstanding Asia-Pacific focus by rebalancing in four main ways: deploying more forces to the Asia-Pacific; basing more ships and aircraft in the region; fielding new capabilities focused on Asia-Pacific challenges; and developing partnerships and intellectual capital across the region.
Deploying more forces to the Asia-Pacific
The most visible element of our rebalance toward the Asia-Pacific region will be an increase in day-to-day military presence. Although it is not the only way we are rebalancing, forces operating in the region show our commitment to the Asia-Pacific and provide a full-time capability to support our allies and partners. About half of the deployed fleet is in the Pacific -- 50 ships on any given day. These ships and their embarked Marines and aircraft train with our allies and partners, reinforce freedom of navigation, and deter conflict. They are also the "first responders" to large-scale crises such as the Great East Asian Earthquake and Tsunami in 2011.