Polymarket removed a forum related to the rescue mission of U.S. military servicemembers amid political pressure, the latest sign of mounting scrutiny around prediction markets.

U.S. and Iranian military forces are searching for a missing American airman after its F-15E fighter jet was shot down over Iran on Friday. One crew member has been rescued, but another is not accounted for.

Rep. Seth Moulton, D-Mass., decried the Polymarket page that allowed users to bet on which day the U.S. would confirm the rescue of the two airmen after an American F-15E fighter jet was shot down over Iran. The lawmaker called the page “DISGUSTING” in an X post.

“They could be your neighbor, a friend, a family member,” Moulton wrote on Friday. “And people are betting on whether or not they’ll be saved.”

In a response on X, Polymarket said: “We took this market down immediately as it does not meet our integrity standards.”

“It should not have been posted, and we are investigating how this slipped through our internal safeguards,” Polymarket wrote.

In a separate X post, Polymarket said it doesn’t “make money or charge any fees on any geopolitical markets.”

In an email to CNBC, Moulton said, “Polymarket didn’t take that market down because it violated their standards. They took it down because we called them out.”

Moulton also said that the Commodity Futures Trading Commission has the authority to regulate prediction market platforms, but it is doing nothing.

“That needs to change, too,” he said. “Yesterday, there were 219 active bets in Polymarket’s ‘war’ category. Today, there are 223. This is spreading, and Congress needs to act.”

Moulton last month banned his staff from using prediction market platforms like Polymarket or Kalshi, a policy that his office believes is the first of its kind in Congress.

“Constituents that we serve should trust us to make decisions based on the right thing for do for our nation, not based on how bets might turn out,” Moulton said Monday on CNBC’s “Squawk Box.”

Moulton also said on X that Donald Trump Jr., the son of President Donald Trump, “is an investor in this dystopian death market and may have access to intelligence that isn’t public yet.”

Requests for comment from Trump Jr. weren’t immediately returned to CNBC.

The Massachusetts lawmaker is part of a growing chorus of voices in Washington calling for stronger oversight of these betting platforms as interest swells.

A group of congressional Democrats introduced legislation late last month that would bar prediction markets from allowing wagers on elections, war and government actions, in addition to sports.

In February, six Democratic senators urged the Commodity Futures Trading Commission to clarify that it will prohibit any contracts related to an individual’s death. These contracts “present dangerous national security risks,” the lawmakers wrote.

The CFTC on Thursday announced lawsuits against three states over what it saw as efforts to circumvent the organization’s sole regulatory authority over prediction markets.

The NFL has also asked prediction market operators to keep specific event contracts that the league deems “objectionable bets” off their platforms. The league outlined examples of event contracts that could be easily manipulated, inherently objectionable, related to officiating, and knowable in advance — and asked that operators refrain from offering such trades.

— CNBC’s Dan Mangan, Azhar Sukri and Luke Fountain contributed to this report.

Disclosure: CNBC and Kalshi have a commercial relationship that includes customer acquisition and a minority investment.

Prediction markets are facing renewed scrutiny from federal lawmakers after wagers about the fate of Iranian leader Ayatollah Ali Khamenei, who was killed in the Saturday bombardment of Iran.

“It’s insane this is legal,” said Sen. Chris Murphy, D-Conn., in a post to X, referring to another post highlighting people who had made money on the invasion.

“People around Trump are profiting off war and death. I’m introducing legislation ASAP to ban this.”

Murphy’s post replied to a tweet that said six “suspected insiders” made $1.2 million betting on a U.S. strike on Iran on the prediction site Polymarket.

CNBC has reached out to Murphy’s office for more details on his proposal.

Murphy’s criticism comes a week after six other Democratic senators, led by Adam Schiff of California, told the Commodity Futures Trading Commission they had serious concerns with prediction market contracts “that incentivize physical injury or death,” saying the contracts “present dangerous national security risks.”

The letter pointed to recent contracts on Polymarket, including ones related to the possible explosion of a NASA spaceship launch, the fate of Venezuela’s authoritarian leader, and Russia’s invasion of Ukraine.

“Gambling on war and death doesn’t just present national security risks, it also raises serious concerns about potential insider trading — presenting unscrupulous government officials with a chance to profit off the new war in Iran,” Schiff said in a post on X on Monday.

“These contracts are immoral. @CFTC can and must ban them.”

Other lawmakers, too, have expressed concern about prediction markets after the invasion. Rep. Mike Levin, D-Calif., said on X that “[p]rediction markets cannot be a vehicle for profiting off advance knowledge of military action.”

“We need answers, transparency, and oversight,” Levin said.

The controversy comes as a new trade group led by President Donald Trump’s former acting Chief of Staff Mick Mulvaney, Gambling Is Not Investing, launched to push tighter guardrails on prediction markets.

Gambling Is Not Investing takes aim at another key market in the prediction space, markets on sports.

Many states in recent years have labored to pass sports betting laws, tapping massive tax revenues from wagers to balance their budgets. Some states now argue that prediction markets, which are federally regulated by the Commodity Futures Trading Commission and often offer betting lines on outcomes in sporting events, are encroaching on their regulated sportsbooks.

“Gambling products — regardless of what you call them — must follow established state and tribal laws,” Mulvaney said.

“Rebranding sports wagering as ‘trading’ or ‘investing’ or ‘predicting’ misleads consumers, undermines responsible gaming protections, and weakens the state and tribal systems built to protect the public and fund vital community services.”

The prediction market Kalshi, in a comment to CNBC, said it “doesn’t allow markets directly tied to death,” regarding betting lines over whether Khamenei would be out of power that have received criticism. The company issued refunds on the market, citing regulations barring wagers on death.

“We included every precaution on this market to make sure people could not trade on the outcome of death,” the company said. “Our rules were clear from the beginning, we never changed them, and we settled based on the rules. We reimbursed all fees and net losses because we thought the UX could have been clearer for users.”

Kalshi CEO Tarek Mansour also responded to Murphy directly in a separate post, saying “regulated prediction markets are not allowed to do war markets.”

“The market you’re posting is unregulated and offshore,” Mansour said.

Disclosure: CNBC and Kalshi have a commercial relationship that includes customer acquisition and a minority investment.