China has made several moves in recent months to advance its ambitious aim to become the trade and transportation hub of Asia. To its west, China has agreed to build a rail line across Central Asia. Beijing also said it would help Vietnam plan three rail lines leading to the countries’ shared border. And China is trying to persuade Russia and North Korea to let it reopen a long-closed port on the Sea of Japan. Kazakhstan RUSSIA Mongolia A long-closed port may be reopened A new rail line across