The sinking of the Iranian warship IRIS Dena by a single Mk 48 torpedo has put renewed focus on the U.S. Navy’s primary undersea weapon, a heavyweight torpedo that first entered operational service in 1972 and has been steadily upgraded for modern naval warfare.

The strike on the IRIS Dena marked the first time since World War II that a U.S. submarine used a torpedo to sink an enemy ship.

"In the Indian Ocean, an American submarine sunk an Iranian warship that thought it was safe in international waters. Instead, it was sunk by a torpedo. Quiet Death," War Secretary Pete Hegseth said at a press conference on Wednesday.

The Navy says the Mk 48 has long served as its principal undersea weapon, designed to "defeat all threat surface ships and submarines in all ocean environments."

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The Mk 48 is a submarine-launched torpedo that uses information from the launching submarine and its own sensors to find and strike submarines or surface ships.

Physically, the weapon is built for destructive power. According to Navy specifications, the torpedo measures 21 inches in diameter, weighs about 3,744 pounds and carries a 650-pound high-explosive warhead.

According to the Department of the Navy's fiscal year 2025 budget estimates, a single Mk 48 torpedo costs approximately $4.2 million.

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Lockheed Martin, one of the Mk 48 torpedo program’s primary contractors, says it can be guided in real time by wire from the launching submarine, allowing operators to update targeting information and adjust its course after launch. 

If the wire connection is lost, the torpedo can switch to autonomous homing, relying on digital guidance systems and onboard signal processing to continue its pursuit independently.

Over time, the torpedo has evolved through hardware variants known as "Mods," each integrating upgraded sensors, guidance and control systems, and propulsion improvements. 

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The current fleet includes the Mod 7 configuration, developed in partnership with the Royal Australian Navy, while Mod 8 is in development and Mod 9 is being pursued as a rapid prototyping effort, according to the Department of War’s Fiscal Year 2024 Annual Report by the Director of Operational Test and Evaluation.

In addition to hardware upgrades, the Mk 48 undergoes recurring software updates known as Advanced Processor Builds, or APBs, which modify tactics, classification algorithms and operator interfaces to improve performance in increasingly complex undersea environments.

EXCLUSIVE: The highest-ranking Minnesotan in Congress is calling for a deeper investigation into allegations that leaders in his state government knowingly ignored evidence of welfare fraud, and he called for those leaders to even face incarceration if proven true.

"People are sick and tired of elected officials having a double standard, being treated differently than they are. They're held accountable for things that they should be held accountable for, when their elected officials are not," House Majority Whip Tom Emmer, R-Minn., told Fox News Digital. 

"If these two guys are dirty, they should be held accountable, and they should serve jail time."

He was referring to Minnesota Gov. Tim Walz and state Attorney General Keith Ellison, two of several witnesses at a high-profile hearing on fraud conducted by the House Oversight Committee on Wednesday.

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Both Walz and Ellison insisted that they were serious about prosecuting fraud in the state's social programs and that they took action to stop it once it was brought to their attention.

But Emmer cited a report by the House Oversight Committee that accused them both of knowing about the fraud earlier than previously thought and delaying public accountability for fear of political retribution from progressives in the state — particularly the Somali community in Minneapolis, who Republicans have accused of taking advantage of the state's welfare system.

"They might have been able to qualify it enough that it wasn't black and white, but if they lied to the committee this morning about knowing about the fraud and when they knew about the fraud and the FBI investigation, that is a criminal act of its own," Emmer told Fox News Digital.

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"So I do believe, depending on this report and what else the majority staff is doing, they very well may want to call them back in and depose them under oath."

He added at another point, "You have maybe 80 to 100,000 Somalis in Minnesota. Tim Walz won with 52%. They made a difference. Keith Ellison won by less than 1%. I think it was 20,000 votes. Makes a difference. So if those are connected, yeah, I mean, this is campaign fraud."

"I've taken accountability for this. I'm not going to run again. I need to spend the time fixing this," Walz said during the hearing. "This does undermine trust in government. Do I wish there were things that could have happened earlier? Yes. But in this job, ‘wish’ didn't do it. I'm looking into where I see it."

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At another point, Walz attributed the rise in fraud statistics to an increase in prosecutions, telling Republicans, "When you catch people and prosecute them, it shows up as a fraud increase."

He also dismissed accusations that he kept whistle-blowers quiet over fear of being seen as Islamophobic, "I can't speak to it because it's not anything I would say."

Ellison, meanwhile, said he was happy to work across bipartisan lines to prosecute fraud.

"I am here to work to improve this system, and there are improvements that can be made," he said. "If we can get out of fixing the blame and get to fixing the problem, that would be an enormous thing for me."

But Emmer, who maintained that further investigation was needed, suggested he doubted their intentions.

"It's power. They want power. In order for them to get power, they need to be elected. In order for them to get elected, they have to cheat in different ways. And that is exactly what they did," Emmer said. "If the Somali community is being used by these public officials to get themselves into office…it sure does look suspect, it needs to be investigated."