Mr Castro, who seeks more foreign trade, investment and aid, appears unwilling to crush the Varela Project outright.

ECONOMIST: Dissent in Cuba

He met Herman Van Rompuy and Jose Manuel Barroso at the White House in a discussion that covered US-EU trade ties, foreign aid and cybersecurity.

BBC: Eurozone crisis: Debt fears loom at White House summit

Lant Pritchett, of the Kennedy School of Government at Harvard, argues that faster global migration would bring huge gains for poor countries, exceeding the combined rewards offered by foreign aid, debt relief and trade reforms proposed under the Doha development round.

ECONOMIST: Too much or not enough?

The International Trade Commission and Trade and Development Agency aid American exporters and domestic firms facing foreign competition.

FORBES: Where to Cut the Federal Budget? Start by Killing Corporate Welfare

The "war on drugs" refers to a hard-line approach undertaken by the US government since the 1970s, which involves strict law enforcement, and foreign aid and military intervention in countries, in order to stamp out the narcotics trade.

BBC: Davos 2013: Soros calls for new strategy on drugs