Zbigniew Brzezinski, former national security advisor to U.S. President Jimmy Carter, wrote: "Mearsheimer and Walt adduce a great deal of factual evidence that over the years Israel has been the beneficiary of privileged — indeed, highly preferential — financial assistance, out of all proportion to what the United States extends to any other country. The massive aid to Israel is in effect a huge entitlement that enriches the relatively prosperous Israelis at the cost of the American taxpayer. Money being fungible, that aid also pays for the very settlements that America opposes and that impede the peace process."[18]