IMHO no they don't, lets take the Iranian oil embargo from last December as a prime example, it has led to higher fuel prices in the rest of the world, creating a knock on effect for the price of food and other goods. The BRIC countries are still buying their oil from Iran, and paying in gold instead of the US$.

Now that the UN has changed the status of Palestine things will become even more interesting, remember that about a month ago the UN called for it's member states to boycott products made in Israel...

Tony