It's a peculiar feature of American relations with Israel that more than a few senior diplomats posted from Jerusalem to Washington were once US citizens. The present Israeli ambassador, Ron Dermer, was born in Miami Beach and carried an American passport until he renounced it in 2005 in order to serve as the Jewish state's economic envoy in DC. When Dermer lived in the US, before moving to Israel two decades ago, he was a Republican party operative. Dermer's predecessor as envoy in Washington, Michael Oren, has now created his own diplomatic uproar with a remarkable attack on Obama that appears at least partly rooted in his disillusionment with the president as leader of the land of Oren's birth. Oren, a New Yorker and US citizen until 2009 when he became ambassador, has stirred outrage by suggesting that the president is not a loyal American. In extracts from a book to be published on Tuesday, Ally: My Journey Across the American-Israeli Divide, Oren accuses the president of policies that imperilled Israel" not least over Iran. Oren wrote in the book of how disturbed he was that Israel's "closest ally had entreated with our deadliest enemy on an existential issue without so much as informing us". Oren, who is now a member of Israel's parliament, writes that Obama is soft on terrorism, a claim open to challenge from those on the end of US drone attacks.