Daniel Shapiro says that Israel's stated support for the establishment of a Palestinian state becomes increasingly difficult with its expansion of settlements.
Shapiro says building settlements raises questions about Israel's intentions. He says that as Israel's closest friend, it is the United States' role to point that out.
He spoke today at the annual conference of the Institute for National Security Studies, a top Israeli think tank.
The international community considers the settlements, built on lands Israel captured in the 1967 war and claimed by the Palestinians, illegal or illegitimate.