PHILADELPHIA (WPVI) -- President Trump announced an agreement with South Korea to build a nuclear-powered submarine in Philadelphia. The announcement, made in a social media post, says it would be made at the Hanwha Philly Shipyard, which South Korea bought to boost its business with the U.S. Navy.

Russia secretly used front companies to buy Western technology and erect a surveillance net in the Arctic where its submarines operate, an investigation shows.

Nuclear-powered submarines use some of the most advanced military technology in the world. These are the ones that are a cut above all the rest.

The Russian Navy exclusively operates titanium-based nuclear submarines that are much more durable. Here's why no other country uses these subs.

Russian Secrets, a new cross-border investigation, reveals the shadowy procurement network behind Russia’s surveillance program Harmony.