The Straits of Malacca provide China with its shortest maritime access to Europe, Africa, and the Middle East. Approximately 80% of its Middle Eastern and African energy imports also pass through the Straits of Malacca. As the world's biggest oil importer, energy security is a key concern for China while current sea routes used to import Middle Eastern and African oil are frequently patrolled by the United States Navy. The sea-route via the Straits of Malacca is roughly , while the distance from Gwadar Port to Xinjiang province is approximately , and another from Xinjiang to China's eastern coast. However, the cost of moving oil overland is far greater. An oil pipeline from Gwadar to China's population centers (not yet built), will cost up to $8/barrel, while the cost of shipping oil from the Persian Gulf to China is $2–3/barrel.