With one phase of nuclear talks over, Iran and six world powers now have an ambitious to-do list that — if implemented — will cut significantly into Iran's bomb-capable technology while giving Tehran quick access to bank accounts, oil markets and other financial assets blocked by international sanctions.

But the deal is far from done. The sides have been working on a substantive result for nearly two years. After a week of grueling negotiations, they managed on Thursday only to draw up a series of commitments that still must be worked out in detail before June 30. That is the deadline agreed on months before negotiators sat down in Lausanne for the final haggling.

If implemented, the undertakings will substantially pare back some Iranian nuclear assets for a decade and restrict others for an additional five years. It would be the first significant success for the United States and its partners in more than a decade of diplomatic efforts focusing on capping Tehran's nuclear advance.

Yet even before the talks culminated in the preliminary outline of what needs be done, both sides warned of the hard work ahead. And the bickering began just a few hours after the sides signed off on their preliminary understanding.

"There is no need to spin using 'fact sheets' so early on," tweeted Iranian Foreign Minister Mohammad Javad Zarif, in a reference to a public document released by the United States listing both sides' commitments. He also questioned some of the assertions contained in the document, such as the speed of a U.S. sanctions drawdown.

According to that text, many of the nuclear limits on Iran would be in place for a decade, while others would last 15 or 20 years. Sanctions related to Iran's nuclear programs would be suspended by the U.S. and the European Union and eased by the U.N. after the International Atomic Energy Agency confirmed Iran's compliance.

The fact sheet also says Tehran is committed to significant cuts in centrifuges, the machines that can spin uranium gas to levels used in nuclear warheads. Of the nearly 20,000 centrifuges Iran now has installed or running at its main enrichment site, the country would be allowed to operate just over 5,000. Much of its enriched stockpiles would be neutralized. A planned reactor would be reconstructed so it produced no weapons-grade plutonium. Monitoring and inspections by the U.N. nuclear agency would be enhanced.

Opponents of the emerging accord, including Israel and Republican leaders in Congress, reacted with skepticism. They criticized the outline for failing to do enough to curb Iran's potential to produce nuclear weapons or to mandate intrusive enough inspections. President Barack Obama, who seeks an Iran nuclear deal as a capstone of his presidency, disagreed.

"This framework would cut off every pathway that Iran could take to develop a nuclear weapon," Obama declared. "This deal is not based on trust. It's based on unprecedented verification."

America's negotiating partners in Europe strongly backed the result. President Francois Hollande of France, who had pushed the U.S. for a tougher stance, endorsed the accord while warning that "sanctions lifted can be re-established if the agreement is not applied."

Obama sought to frame the deal as necessary to reduce the chances of the combustible Middle East becoming even more unstable with the introduction of a nuclear-armed Iran. Many fear that would spark an arms race that could spiral out of control in a region rife with sectarian rivalry, terrorist threats and weak or failed states.

Obama said he had spoken with Saudi Arabia's King Salman and that he'd invite him and other Arab leaders to the presidential retreat at Camp David this spring to discuss security strategy. The Sunni-majority Saudis have made veiled threats about creating their own nuclear program to counter Shia-led Iran.

The American leader also spoke by telephone with Israeli Prime Minister Benjamin Netanyahu, perhaps the sharpest critic of the diplomacy with Iran. Netanyahu told Obama a deal based on the agreement "would threaten the survival of Israel." The White House said Obama assured Netanyahu that the agreement would not diminish U.S. concerns about Iran's sponsorship of terrorism and threats toward Israel.

Obama saved his sharpest words for members of Congress who have threatened to either try to kill the agreement or approve new sanctions against Iran. Appearing in the Rose Garden of the White House, he said the issues at stake are "bigger than politics."

"These are matters of war and peace," Obama said, and if Congress kills the agreement "international unity will collapse, and the path to conflict will widen."

Hawks on Capitol Hill reacted slowly to the news. House Speaker John Boehner said it would be "naive to suggest the Iranian regime will not continue to use its nuclear program, and any economic relief, to further destabilize the region."

Senate Foreign Relations Committee Chairman Bob Corker, R-Tenn., said his panel would vote this month on legislation giving Congress the right to vote on a final deal. Freshman Sen. Tom Cotton, R-Ark., who penned a letter that many GOP senators signed last month to Iran's leaders, said he would work "to protect America from this very dangerous proposal."

In a joint statement, European Union foreign policy chief Federica Mogherini and Iran's Zarif called the agreement a "decisive step."

All sides spoke with a note of caution.

"We have taken a major step, but are still some way away from where we want to be," Zarif told reporters, even as he voiced hope that a final agreement might ease suspicion between the U.S. and Iran, which haven't had diplomatic relations since the 1979 overthrow of the shah and the subsequent U.S. Embassy hostage crisis in Tehran.

Kerry lashed out at critics who wanted tougher caps on Iran's nuclear assets.

"Simply demanding that Iran capitulate makes a nice sound bite, but it is not a policy," Kerry said. "It is not a realistic plan."