A vast trove of secret State Department cables obtained by the website WikiLeaks has exposed the inner workings of U.S. diplomacy, as well as bluntly candid assessments by American diplomats, according to news organizations granted advance access to the more than 250,000 confidential documents.

The documents suggest U.S. diplomats were ordered to engage in low-level spying by obtaining foreign diplomats’ personal information, such as frequent-flier and credit card numbers, presumably to better track their movements.

The cables also expose the sensitive diplomacy involved in winning sanctions against Iran; U.S. officials’ attempts to remove highly enriched uranium from Pakistan; and new information on how North Korea is believed to have aided Tehran’s weaponry program, giving it advanced missiles that could allow it to strike Moscow and major Western European cities.

Many of the insights gleaned from the documents are not surprising by themselves. Newspapers, for instance, have long reported that Arab nations are privately much more concerned about Iran’s nuclear program than they admit publicly, and the cables document such concerns.

Still, such analysis rarely has the imprimatur of a U.S. government document, and the cables quote Arab officials by name expressing concerns they have not expressed in public.

One cable asserts that King Abdullah of Saudi Arabia repeatedly asked the United States to “cut off the head of the snake”– presumably meaning to attack Iran’s nuclear program — while there was still time. Another quotes a senior Saudi official as warning that if Iran is not stopped, Persian Gulf Arab states would develop their own nuclear weapons.

Even when the documents merely confirm foreigners’ suspicions, they could embarrass the Obama administration. In cables drafted by U.S. diplomats, Russian Prime Minister Vladimir Putin is described as an “alpha-dog,” Afghan President Hamid Karzai is “driven by paranoia,” and German Chancellor Angela Merkel allegedly “avoids risk and is rarely creative.”

Libyan leader Moammar Gaddafi is accompanied everywhere by a “voluptuous blonde” Ukrainian nurse. Silvio Berlusconi, the Italian premier, “appears increasingly to be the mouthpiece of Putin” in Europe after receiving “lavish gifts” and lucrative energy contracts and the involvement of a “shadowy” Italian intermediary.

The documents reveal how U.S. embassies have relied on foreign officials for insight into policy. The German magazine Der Spiegel reported that Defense Minister Karl-Theodor zu Guttenberg “tattled on his colleague,” German Foreign Minister Guido Westerwelle, “telling the U.S. ambassador that Westerwelle was the real barrier to the Americans’ request for an increase in the number of German troops in Afghanistan.”

WikiLeaks granted advance access to a number of news organizations, including Der Spiegel, The New York Times, the Guardian newspaper in Britain, El Pais in Spain and Le Monde in France. Those outlets began publishing reports on the cables online Sunday afternoon.

Most of the cables appear to have been drafted over the past several years — including some as recently as February — but others reach as far back as 1966.

Some of the cables, according to the Times, disclosed information long rumored but never confirmed: U.S. diplomats offered various countries incentives, like a meeting with President Obama or even millions of dollars, in exchange for accepting detainees from the Guantanamo Bay prison. China’s Politburo directed the intrusion into Google’s computer systems in that country. U.S. and South Korean diplomats have discussed how to handle the potential collapse of North Korea.

The Obama administration had dispatched envoys to warn foreign governments that the pending release of the information could damage relations, with Secretary of State Hillary Clinton personally calling a number of her counterparts.

Diplomats fear that the disclosure of the cables, many of which weren’t meant to be declassified for 20 years or more, will chill unvarnished conversations with foreign governments.

“its very nature, field reporting to Washington is candid and often incomplete information,” White House press secretary Robert Gibbs said in a statement. “It is not an expression of policy, nor does it always shape final policy decisions.

“Nevertheless,” he added, “these cables could compromise private discussions with foreign governments and opposition leaders, and when the substance of private conversations is printed on the front pages of newspapers across the world, it can deeply impact not only U.S. foreign policy interests, but those of our allies and friends around the world.”

WikiLeaks posted a limited number of the cables on a website, cablegate.wikileaks.org. It said it planned to release more than 250,000 documents in stages over the next few months.

WikiLeaks has not disclosed the source of the materials, but suspicion has centered on Pfc. Bradley Manning, an Army intelligence analyst. The military arrested him this year, charging him with the downloading and transfer of classified material.

WikiLeaks, founded in 2006 by former computer hacker Julian Assange, has released two other major tranches of data based on secret U.S. documents — one about the war in Afghanistan, the other about the war in Iraq.

The organization has come under stress since then, with several members quitting after citing differences with Assange and the direction of the group. As well, Assange is facing allegations in Sweden of rape and sexual harassment, which he has denied, saying the charges are part of a U.S.-orchestrated smear campaign.