There is a federal statute that requires that anyone -- even a former U.S. President -- doing political or public affairs work on behalf of a foreign principal (country, official, etc.), must register as an "Agent of a Foreign Principal" with the Department of Justice.
Has former President Clinton done so? If not, why? His spokesman today confirmed "one phone call" that Mr. Clinton received, and by way of doing that confirmed that the former President was doing work for the United Arab Emirates on the Dubai Port Deal.