TOKYO -- Japan's first submarine powered by lithium-ion batteries was launched on Thursday, symbolizing domestic defense contractors' hopes that innovations can allow the industry to survive amid renewed pressure from Washington to procure more American military gear.

The 84-meter Oryu was lowered into the water at the Kobe shipyard of Mitsubishi Heavy Industries, the vessel's developer, after being christened with a bottle of sake. The submarine can reach speeds of roughly 20 knots and displaces 2,950 tons. It will be delivered to the Japan Maritime Self-Defense Force in March 2020.

The Oryu is the eleventh submarine based on the Soryu's design. Soryu-class vessels, which started being built in 2005, are among the largest diesel-electric submarines in the world.

But the Oryu is a vastly updated version of the Soryu, the biggest change being the replacement of lead-acid batteries with lithium-ion ones. Mitsubishi Heavy tapped GS Yuasa to supply the high-performance batteries, which store about double the power.

Submarine batteries are recharged by the energy generated by Oryu's diesel engines. The vessel switches to batteries during operations and actual combat in order to silence the engines and become harder to detect. The lithium-ion batteries radically extend the sub's range and time it can spend underwater.

But amid the joyous occasion of the Oryu's launch, Mitsubishi Heavy executives maintained grim expressions. Washington has been pressuring Tokyo to expand procurement of American military gear as a means of cutting the countries' trade imbalance. Such a development would leave Japanese defense contractors with fewer orders.

U.S. President Donald Trump urged Japanese Prime Minister Shinzo Abe to buy more American weapons during a bilateral summit last week. "It is important for us to continue to introduce sophisticated equipment, including American equipment, so that Japan's defense capability can be strengthened," Abe reportedly told Trump.

In recent years, Japan has been ramping up procurement of U.S. equipment, such as the Aegis Ashore missile shield. Up through fiscal 2011, Tokyo's purchases through Washington's Foreign Military Sales program had been less than 100 billion yen ($879 million) a year. That surpassed 400 billion yen this fiscal year.

While these purchases allow Japan to get its hands on high-performance American military hardware, the benefits to the domestic defense industry have been few and far between. Meanwhile, exports of Japanese military equipment have stalled. The Abe government had sought to have Australia order Soryu-class submarines, built by Mitsubishi Heavy and Kawasaki Heavy Industries, but Canberra opted in 2016 to purchase French-made vessels instead. Kawasaki Heavy has yet to export any of its P-1 military patrol aircraft. Plans to domestically develop a successor to the aging fleet of F-2 fighter jets are under a cloud.

But when it comes to military vessels, Japan possesses specialized technology supported by a robust shipbuilding infrastructure. Japan's commercial shipbuilding industry is being squeezed by Chinese and South Korean rivals, and Japan's defense industry is under attack by U.S. military imports. The only domain left for Japan's heavy industry is submarines. The Oryu will be the last of the Soryu class. For the next generation, the Oryu's advanced technology is expected to be repurposed into a 3,000-ton submarine.