Qualcomm, one of the world’s largest chip makers, has spent the last four months fending off a hostile takeover from Broadcom, a Singaporean rival. The fate of the proposed takeover may now be in jeopardy because of a little-known committee of top administration officials who meet in secret, wielding power to kill the biggest multibillion-dollar global deals.

The Committee on Foreign Investment in the United States, or Cfius (pronounced SIFF-ee-yuss), investigates mergers that could result in control of an American business by a foreign individual or company, judging whether deals could threaten national interests. In a letter on Monday, the committee said that a deal for Qualcomm, whose semiconductors will be used in the next generation of ultrafast wireless networks known as 5G, could pose a risk to national security.

It appears to be the first time the committee has intervened on a deal before it has been finalized, a signal that Cfius may play a more prominent role in the Trump administration’s America First policymaking.

Cfius is the ‘ultimate regulatory bazooka’

The committee is made up of members of the State, Defense, Justice, Commerce, Energy and Homeland Security departments, and is led by the treasury secretary. These days, that means Steven Mnuchin.