Austin-based defense startup Saronic has raised a $600 million Series C to build an autonomous ship factory called “Port Alpha,” it announced yesterday, quadrupling its valuation to $4 billion from its last round. 

Investor Elad Gil led the round, with General Catalyst joining existing investors Andreessen Horowitz, 8VC, and Caffeinated Capital, among others.

That should make Saronic the second, possibly third, most valuable defense tech startup in the U.S. after Anduril’s last round valued it at $14 billion. Shield AI could beat that, though, as it is reportedly in talks to hit a $5 billion valuation on a new round of funding. (Anduril is in talks to raise again at double its valuation, to $28 billion.)

Saronic isn’t the only defense tech darling with big manufacturing ambitions: Anduril, for example, announced plans to build a billion-dollar megafactory in Ohio last month.

Saronic hasn’t found a site for Port Alpha yet but is actively searching, a spokesperson confirmed to TechCrunch. Operations at the port, which Saronic is calling the ‘shipyard of the future,’ are slated to begin within five years, Saronic’s co-founder and CEO Dino Mavrookas told Defense News.

Saronic has already developed three models of autonomous surface vessels (ASVs) that are up to 24 feet long – about half as long as a modern lifeboat. But Saronic says the factory will also build large unmanned ships, while bolstering U.S. shipbuilding capacity compared to China.

Unmanned ships are a hot trend in naval warfare, in part thanks to Ukraine’s successful use of drone ships to drive the Russian Navy out of Crimea, despite Ukraine having effectively no manned navy of its own. 

Saronic has now raised almost $850 million, Mavrookas said on CNBC, attributing the quadrupled valuation to Saronic’s speed at developing new vessels and software.

Saronic’s raise is the latest sign that defense tech continues to hit new highs in Silicon Valley, buoyed by similar monster rounds.