North Korea has spent the last year bolstering its fleet with new nuclear weapons, including an underwater drone, destroyers, and its first operational missile submarine, which was displayed on Friday.

Historically, North Korea’s navy has been dwarfed by the country’s land forces and overshadowed by its quickly developing ballistic missile program.

Now, North Korean leader Kim Jong Un has stated that the navy would play an important part in the country’s nuclear deterrent, which observers believe will ensure support among naval commanders and increase national pride.

“Until quite recently, Kim appeared to largely neglect naval nuclear programs,” said Ankit Panda of the Carnegie Endowment for International Peace in the United States. “The recent refocus on naval nuclear capabilities has most likely been welcomed by the Korean People’s Navy.”

Here is what we know about North Korea’s navy and its latest advancements.