Among the CFIUS staffers playing a role in identifying non-filers, alongside CFIUS Staff Chairman Stephen Hanson and Treasury Deputy Assistant Secretary for Investment Security Aimen Mir, is Brian Reissaus, a former member of the Defense Security Service, an agency of the U.S. Department of Defense, according to the sources. Reissaus will often be the CFIUS staffer reaching out to companies, the sources said.

A Treasury spokesman declined to comment on behalf of CFIUS and the staffers. Chinese government officials declined to comment on CFIUS's new focus.

CAUGHT OFF-GUARD

CFIUS's crackdown on these non-notified transactions shows how the agency's focus has expanded beyond traditional sectors of national security concern, such as aerospace and semiconductors, to less obvious areas ranging from commercial IT and agriculture to biomedical science and electronics.

Companies whose deals are reviewed by CFIUS without having made voluntary filings risk delays in completing them and uncertainty over their investment plans, lawyers say.

In the case of Fosun, to ensure CFIUS approval Ironshore agreed to sell Wright last month to former American International Group Inc CEO Hank Greenberg's Starr Companies, according to the sources.

In light of this divestment and other conversations it had with CFIUS, the company has reset the CFIUS review process by making another filing with the panel, and an outcome is expected in the coming weeks, one of the sources added.

In the interim, Fosun has been exploring selling Ironshore outright as an alternative to an IPO, according to the sources.

HELL OR HIGH WATER

Some companies resist filing for a CFIUS review voluntarily because they fear that addressing this issue during their tough merger negotiations will add an extra layer of complexity to the talks, and some times risk complicating them to the point that a deal is not reached.