What is the fine-grained topic of the following text: The future USS Lyndon B. Johnson (DDG 1002), the third and final ship of the Zumwalt-class – the U.S. Navy’s largest and technologically most advanced class of guided-missile destroyers — was launched at the General Dynamics Bath Iron Works (BIW) shipyard in Maine on December 9, according to Naval Sea Systems Command. Only return the topic.
Launch of the future USS Lyndon B. Johnson (DDG 1002) Zumwalt-class destroyer