do citizens and governments of wealthy countries owe those living in poor countries?

Jeffrey Sachs, a prominent economist and frequent critic of globalization, has argued that $70 billion a year in development aid is needed to lift people out of extreme poverty. This figure would require all members of the Organization of Economic Cooperation and Development (OECD), an organization of the richest, most industrialized economies in the world, donate 0.7% of their Gross National Product (GNP – a measure of the total wealth produced in the national economy each year) to development aid. Currently, few OECD countries meet this goal, with only Denmark, Norway, Sweden, Netherlands and Luxembourg giving 0.7% or more. The U.S. gives the most overall amount (because it has the largest economy), but contributes only about 0.2% of GNP to development aid. Behind these variations in levels of aid, are different views on what obligations the rich countries owe the poor.

What obligations, if any, do citizens and governments of wealthy countries owe those living in poor countries? What are the limits of this obligation? In other words, how much should wealthy countries do to assist the poor around the world? Should the U.S. give more in development aid? Should, as some groups have argued, there be a global tax on financial transactions to help fund economic development in poorer countries?