The confidential cables, most of which date from 2007 to last February, also reveal how the State Department has ordered diplomats to spy on foreign officials and even to obtain their credit card and frequent flier numbers.
The memos recount closed-door remarks that could stoke scandal, including Yemen's president telling a top US general "We'll continue saying the bombs are ours, not yours," when discussing secretive US strikes on Al-Qaeda”.
A description of Libyan leader Moamer Kadhafi showed him requiring the near-constant assistance of a "voluptuous blond" Ukrainian nurse.
The New York Times, Britain's The Guardian, Germany's Der Spiegel, France's Le Monde and Spain's El Pais published the first batch of the documents on Sunday, saying more would follow in the coming days.
Despite coming under a cyber attack that took down its main website earlier in the day, WikiLeaks started publishing the 251,287 cables - 15,652 of which are classified "secret" - from 274 US embassies around the world on a sub-website.
In an introduction, it painted the United States as a hypocritical superpower and attacked "the contradictions between the US's public persona and what it says behind closed doors”.
The White House hit back, saying the release was a "reckless and dangerous action" that put lives in danger.