The United States remains ready to upset key allies Israel and Saudi Arabia by securing a swift nuclear deal with Iran despite the failure of talks in Geneva, US-based analysts said Sunday.

While Tehran remained under the greatest pressure to reach a speedy deal with the major powers, they said, Washington was anxious to take advantage of Iran's willingness to negotiate an accord and avert future conflict in the Middle East.

Three grueling days of discussions between Iran, the United States, China, Russia, Britain, France and Germany ended early Sunday without agreement.

The parties had been hoping to broker an accord that would curb Tehran's nuclear program in exchange for sanctions relief.

By searching for a deal in Geneva, the US was "maybe trying to go a little too far, too fast, but they were induced by the Iranian enthusiasm," according to Hussein Ibish, a senior fellow at the American Task Force on Palestine.

"It is really the convergence of US and Iranian desires to avoid an even deeper confrontation over the nuclear file that makes an agreement possible at this stage," he added, citing the 10-year impasse concerning the nuclear program, which Western powers suspect of being geared towards producing an atomic bomb rather than peaceful civilian uses.

Alireza Nader, a senior international policy analyst at the RAND Corporation think-tank, questioned the suggestion that the United States was "rushing" to reach a deal at any cost with Iran, with whom it has had no diplomatic relations since 1980.

Despite the historic phone call between US President Barack Obama and Iranian counterpart Hassan Rouhani at the end of September, any improvement in relations between the two sides must continue to be viewed in the context of the decades of mistrust and animosity that preceded it.

However, it was the clear the the United States was keen on reaching an agreement in Geneva, because a "a deal as a first step (provides) an opportunity to stop Iran from moving towards a nuclear weapons breakout capability."

Nader said the Obama administration had always favored a diplomatic solution to the nuclear stand-off.

"I don't think the US position has changed in the last few months," Nader said. "What we have seen now is the willingness by Iran to negotiate."

Iran was keen to see an easing crippling sanctions, notably restrictions, which have frozen overseas assets worth several billion dollars.

US Secretary of State John Kerry meanwhile defended Washington against the accusation that it was pursuing a deal with Tehran at all costs.

"We are not blind, and I don't think we're stupid," Kerry said.

He also sent a new message to Israel and Saudi Arabia, who have grown increasingly alarmed at the warming of US-Iranian ties, saying Washington had a "pretty strong sense of how to measure whether or not we are acting in the interests of our country and of the globe, and particularly of our allies like Israel and Gulf States."

Israel and Saudi Arabia anxious

Analysts are adamant that Israel and Saudi Arabia remain resolutely opposed to any deal between Washington and Tehran.

"Both the Israelis and the Saudis have indicated publicly they want the United States to go to war with Iran," said Trita Parsi, president of the National Iranian American Council.

"If there is a deal, there will not be a war, that's why they are upset."

RAND Corporation expert Nader also noted the "anxiety" of Israel and Saudi Arabia, who likely feared that a US-Iran deal would be harmful to their long-term strategic interests.

"They are worried about Iranian-American relations improving to their detriment," Nader said. The possibility of Iran playing a bigger role in regional affairs "creates anxiety for Israel and Saudi Arabia."

Israeli Prime Minister Benjamin Netanyahu said Sunday Israel would do all it could to "convince world powers to avoid a bad deal."

American Task Force on Palestine expert Ibish said Gulf states already "seem to be concluding, with alarm, that the US is morphing from the guarantor of regional stability to a broker of unsatisfactory and tenuous agreements with regimes that should be confronted or contained."

"The Saudis and other Gulf states are starting to ask the question 'Why does the US seem to be developing a panel of rewarding its enemies and punishing its friends?'"