Amos Guiora knows all about the pitfalls of targeted assassinations, both in terms of legal process and the risk of killing the wrong people or causing civilian casualties.
The University of Utah law professor spent many years in the Israel Defence Forces, including time as a legal adviser in the Gaza Strip, where such strikes are common. He knows what it feels like when people weigh life-and-death decisions.
Yet Guiora - no dove on such matters - confessed he was "deeply concerned" about President Barack Obama's own "kill list" of terrorists and the way they are eliminated by missiles fired from robot drones.
He believes United States policy has not tightly defined how people get on the list, leaving it open to legal and moral problems when the order to kill leaves Obama's desk.
"He is making a decision largely devoid of external review," Guiora said, characterising the US's apparent methodology for deciding who is a terrorist as "loosey goosey".
Indeed, newspaper revelations about the "kill list" have shown the Obama Administration defines a militant as any military-age male in the strike zone when its drone attacks. That has raised the hackles of many who saw Obama as somehow more sophisticated on terrorism issues than his predecessor, George W. Bush.
But Guiora does not view it that way. "If Bush did what Obama has been doing, then journalists would have been all over it," he said.
Having come to office on a powerful message of breaking with Bush, Obama has in fact built on his predecessor's national security tactics.
He has presided over a massive expansion of secret surveillance of American citizens by the National Security Agency. He has launched a ferocious and unprecedented crackdown on whistleblowers. He has made more government documents classified than any previous President.
He has broken his promise to close the controversial Guantanamo Bay prison and pressed on with prosecutions via secretive military tribunals, rather than civilian courts. He has preserved CIA renditions.
In last week's New York Times article that detailed the "kill list", Bush's last CIA director, Michael Hayden, said Obama should open the process to more public scrutiny. "Democracies do not make war on the basis of legal memos locked in a [Department of Justice] safe," he told the newspaper.
Even more pertinently, Aaron David Miller, a long-term Middle East policy adviser to both Republican and Democratic Administrations, delivered a damning verdict in a recent issue of Foreign Policy magazine. He wrote bluntly: "Barack Obama has become George W. Bush on steroids."
The Administration used the Espionage Act - an obscure World War I anti-spy law - six times. That is more uses in three years than under all previous Presidents combined. Cases include John Kiriakou, a CIA agent who leaked details of waterboarding, and Thomas Drake, who revealed the inflated costs of a National Security Agency data collection project that had been contracted out.
The development fits with a growing level of secrecy in government under Obama. Last week a report by the Information Security Oversight Office revealed 2011 saw US officials create more than 92 million classified documents: the most ever and 16 million more than the year before.
"We are seeing the reversal of the proper flow of information between the Government and the governed. It is probably the fundamental civil liberties issue of our time," said Elizabeth Goitein, a national security expert at the Brennan Centre for Justice. "The national security establishment is getting bigger and bigger."
The drone programme and "kill list" have emerged as most central to Obama's hardline national security policy. In January 2009, when Obama came to power, the drone programme existed only for Pakistan and had made 44 strikes in five years. With Obama it expanded to Afghanistan, Yemen and Somalia with more than 250 strikes. Civilian casualties are common. Obama has deliberately killed US citizens, including radical cleric Anwar al-Awlaki last September, and accidentally killed others, such as Awlaki's 16-year-old son, Abdul-Rahman.
Yet for some, politics seems moot.
Jesselyn Radack was a Justice Department ethics adviser under Bush who became a whistleblower over violations of the legal rights of "American Taleban" John Walker Lindh. Now she works for the Government Accountability Project, defending fellow whistleblowers. She campaigned for Obama, donated money and voted for him.
"Whoever gets elected, whether it's Obama or Romney, they are going to continue this very dangerous path," she said. "It creates a constitutional crisis for our country. A crisis of who we are as Americans. You can't be a free society when all this happens in secret."
High in the Utah mountain deserts a chamber of American secrets is being built.
The innocuously named Utah Data Centre is being built for the National Security Agency near a tiny town called Bluffdale.
When completed next year, the heavily fortified US$2 billion ($2.65 billion) building, which is self-sufficient with its own power plant, will be five times the size of the US Capitol in Washington DC.
Gigantic servers will store vast amounts of data from ordinary citizens to be sifted and mined for intelligence clues. It will cover everything from emails to phone calls to credit card bills.
The centre is the most obvious sign of how the operations and scope of the NSA have grown since the 9/11 terrorist attacks. Under President George W.
Bush, a key part was a secret "warrantless wiretapping'' programme that was scrapped when it was exposed. However, in 2008 Congress passed a bill that effectively allowed the programme to continue.