Assange said there were "enormous expectations in the United States" about the material and that "some of that expectation will be partly answered", with "a lot of fascinating angles" in the documents.
"Do they show interesting features of US power factions? Yes they do," he said, addressing an anniversary event in Berlin via videolink.
On why WikiLeaks was holding back for now, he added that "if we're going to make a major publication in relation to the United States at a particular hour, we don't do it at 3am," referring to the time in the eastern United States.
He also said that "we hope to be publishing every week for the next 10 weeks," promising documents on the subjects of war, arms, oil, Google and mass surveillance.
Assange -- speaking from the Ecuadorean embassy in London, where he has been holed up for over four years to avoid being extradited to Sweden to face rape allegations -- hailed WikiLeaks for releasing 10 million documents over the past decade, exposing state and corporate secrets.
He pledged that WikiLeaks would seek to expand its activities with extra staff and new media partnerships, with plans to hire 100 more journalists over the next three years.
"We're going to need... an army to defend us from the pressure that is already starting to arrive," said Assange, wearing a black T-shirt with the word 'truth' on it.
On the eve of the US Democratic Party convention in July, WikiLeaks published some 20,000 internal emails pointing at an apparent bias of its leaders for Clinton during the primary campaign.
Assange charged that WikiLeaks was now the target of a witch hunt orchestrated in particular by Clinton, likening it to the repression of American communists in the 1950s driven by then senator Joseph McCarthy.
Assange said WikiLeaks would scale up to "amplify our publications and to defend us against what is really a quite remarkable McCarthyist push in the United States at the moment, principally by Hillary Clinton and her allies because she happens to be the person being exposed at the moment".
Asked whether he felt affinity with Clinton's Republican rival Donald Trump, he said: "I feel personal affinity with all human beings. Through understanding someone, you can feel sorry for them.
"I certainly feel sorry for Hillary Clinton and Donald Trump. These are two people who are tormented by their ambitions."
