I'd have to dig, but my guess is the EO follows legislation.
The Statute. Section 5021 of the Omnibus Trade and Competitiveness Act of 1988 amended Section 721 of the Defense Production Act of 1950 to provide authority to the President to suspend or prohibit any foreign acquisition, merger or takeover of a U.S. corporation that is determined to threaten the national security of the United States. ...http://www.ustreas.gov/offices/international-affairs/exon-florio/
Unable to pacify Congress with data and studies arguing the adequacy of the existing regulatory regime, the White House had to make a substantial and publicly visible move. It pledged to Congress that it would create a high-level interagency committee, reporting directly to the President, charged with monitoring incoming investments. While the powers of the proposed committee, CFIUS, would not approach those of the kind of screening agency some in Congress had proposed, the pledge to create the committee was a politically meaningful gesture to the policy entrepreneurs in Congress who had invested considerable political capital in the IFDI issue. After all, the establishment of CFIUS added a new bureaucratic entity to the executive branch that the President did not really want and created a potential entry point for congressional intervention in the President’s conduct of IFDI policy. When the White House outlined the plan for establishing CFIUS, policymakers in Congress recognized the gesture for what it was and welcomed the proposal. The favorable response moved the White House to seek immediate implementation of the plan.CFIUS Info