Obama can threaten corporations ad infinitum, but he can only stop inversions by encouraging Congress to reform the code so that U.S. multinationals have the same tax and investment advantages as foreign ones. By inverting, corporations are only acting in their best interests and in the interests of their shareholders, and they should be praised for doing that.
Honorable Members of Congress, you could immediately assist Ukraine and other countries by amending the Natural Gas Act to ensure that the Energy Department approves LNG export applications within a short period of time.
You could also pass legislation allowing LNG to be exported to all World Trade Organization members, irrespective of whether they have free trade agreements with the United States. You could go still further, and cease to require approval for LNG exports.