Impetus for reform first began, however, when the China National Offshore Oil Corporation publicly announced an interest in UNOCAL in 2005, and even earlier that same year, when a GAO report revealed the lack of Congressional oversight and the degree to which some CFIUS transactions were escaping formal investigation through withdrawal of applications, among other things.

More generally, the bill establishes more stringent rules for the review and formal investigation of transactions, especially those involving foreign governments or critical infrastructure assets.

In general, then, the bill's provisions convey the seriousness with which Congress expects the CFIUS agencies to approach future reviews.

• Transactions that involve foreign governments, a threat to national security, or control of critical infrastructure must be subject to a 45-day formal investigation, except that exceptions are possible for foreign government transactions if the Secretary or Deputy Secretary of Treasury and the lead agency certify that there is no national security threat.

In the case of foreign-government transactions, CFIUS must also consider the relevant country's compliance with US and multilateral counter-terrorism, non-proliferation, and export control regimes.

And it requires CFIUS to publish guidelines concerning the types of transactions that have presented national security considerations, which could be helpful for companies trying to determine whether to make the so-called "voluntary" filing decision, especially now that withdrawals will be more closely regulated.