WASHINGTON--U.S. Treasury wants to enhance the power of a little-known, secretive government committee to review deals made between U.S. firms and foreign investors.

This comes as high-profile deals involving foreign investment in the U.S. — like Chinese firm ByteDance’s ownership of popular social media app TikTok and Japanese firm Nippon Steel’s bid to purchase Pittsburgh-based U.S. Steel Corp. receive increased scrutiny by lawmakers and even President Joe Biden.

A new proposed rulemaking would strengthen powers for the interagency Committee on Foreign Investment in the United States — known as CFIUS — which is tasked with investigating corporate deals for national security concerns and holds power to force the company to divest ownership or change major parts of the firm.

The rulemaking — if finalized — would expand the committee's subpoena authority, allow the committee to request more information from parties to a proposed sale and expand circumstances when fines can be imposed and their size — from $250,000 to $5 million, where there are misstatements, omissions and failure to file mandatory declarations.

The proposed change comes as the convergence of national security concerns related to foreign investment have increased — as competition intensifies between the world's biggest powers and the U.S. focuses on growing its domestic supply chains.

President Joe Biden came out in opposition to the planned sale of U.S. Steel to Nippon Steel of Japan, saying in March that the U.S. needs to “maintain strong American steel companies powered by American steelworkers.” Japanese Prime Minister Fumio Kishida said on Wednesday during a White House press conference that he hopes discussions on Nippon “will unfold in directions that would be positive for both sides.”

Nippon Steel announced in December that it planned to buy the Pittsburgh-based steel producer for $14.1 billion in cash, raising concerns about what the transaction could mean for unionized workers, supply chains and U.S. national security.

Treasury's Assistant Secretary for Investment Security Paul Rosen said the rulemaking is meant to “more effectively deter violations, promote compliance and swiftly address national security risks in connection with CFIUS reviews.”

John Carlin, the former Justice Department national security chief and a partner at the Paul Weiss law firm, said the proposed rule shows how “corporations are on the front lines of national security policy and how seriously the government is taking foreign investments.”

“The announcement today is all about adding tools for them to investigate and more actively and aggressively enforce their authorities,” he said. He added that it was going “to act as an incentive for people to really scrub deals to see whether or not they need to file.”

“It really makes CFIUS more of an enforcement agency” by broadening their subpoena power, he said.

Another deal under CFIUS review is the ownership of popular social media app, TikTok. CFIUS’ review of the social media app goes back at least to 2019, though no movement has been made on that review. The U.S. House of Representatives has since passed a bill that would force ByteDance to either sell the app or have it banned in the U.S.

Asked at a press conference in Beijing on Monday about TikTok, Treasury Secretary Janet Yellen said that she supported the administration’s efforts to address national security issues that relate to sensitive personal data. “This is a legitimate concern,” she said.

“Many US social apps are not allowed to operate in China,” Yellen said. “We would like to find a way forward.”

Philip Ludvigson, a partner at the law firm King & Spalding, said the proposed regulations “are yet another indicator of an increasingly aggressive posture in protecting national security.” Ludvigson is a former director for CFIUS Monitoring & Enforcement.

“CFIUS clearly intends to issue more and bigger penalties than ever before, using an enhanced subpoena authority wherever necessary,” he said.

The U.S. has also begun reviewing certain transactions made between U.S. firms and those in China.

President Joe Biden signed an executive order last August to block and regulate high-tech U.S.-based investments going toward China.