Biden suggests nuclear talks with Iran may resume.

ROME — President Biden suggested on Saturday that talks to restart a nuclear accord with Iran, a delicate diplomatic deal struck in 2015 and unraveled by the Trump administration, may move forward.

“They’re scheduled to resume,” Mr. Biden said at the Group of 20 summit, just before he entered a meeting with President Emmanuel Macron of France, Chancellor Angela Merkel of Germany and Prime Minister Boris Johnson of Britain to discuss rejoining the pact.

In a hastily released joint statement, though, the group seemed to put the brakes on Mr. Biden’s assertion that talks would definitely resume.

The statement said the leaders, whose nations are parties to the accord, “welcome President Biden’s clearly demonstrated commitment to return the U.S. to full compliance” with the agreement and “stay in full compliance, so long as Iran does.”

Mr. Biden’s advisers had said ahead of the summit not to expect a major development on the pact, but the president’s comments seemed to suggest an openness to move forward, if not a concrete step.

In the vortex of global challenges facing the Group of 20 leaders — the tenacious coronavirus, the disrupted economy and the warming climate — the breakdown of talks with Iran represents a less prominent but no less vexing problem for the United States and its European allies.

In Saturday’s meeting, which was closed to the news media, Mr. Biden and his counterparts were expected to discuss efforts to revive the 2015 nuclear accord, which the president’s predecessor, Donald J. Trump, abandoned in 2018, calling it insufficiently strict.

Under the agreement, Iran sharply curtailed its nuclear activities in verifiable ways, aimed at ensuring that it could not make an atomic bomb, and the United States rescinded some sanctions that had severely crimped Iran’s economy.

Since the U.S. repudiation of the agreement, and the restoration of sanctions, Iran is no longer abiding by its terms, either. According to U.N. monitoring reports, Iran has made significant advances in enriching uranium, the nuclear fuel that can be used for both peaceful pursuits and for weapons. It now has far more enriched uranium than it did in 2018, and has enriched it closer to the very high level needed to make a bomb.

Although Iran has repeatedly pledged that it will never become a nuclear-weapons state, it is believed to be close to crossing an important threshold, having amassed roughly enough uranium for fueling a bomb.

Mr. Biden has said he wants to restore U.S. participation in the agreement. The other parties to the accord — Britain, China, France, Germany and Russia — have been seeking ways to save it.

But talks with Iran on this issue have basically been stalled since the June election of Iran’s hard-line president, Ebrahim Raisi, who has insisted that the United States return to compliance first, promise to never abandon the accord again and give up any thought of renegotiating its terms.

Biden administration officials have suggested that time is running out to salvage the agreement.

On Wednesday, Iran’s deputy foreign minister said that Iran intended to participate in talks in Vienna on reviving the accord before Nov. 30, but as of this weekend, a date had not been set.

Outside experts who have followed the ups and downs of the accord’s history have turned increasingly skeptical about the prospects for saving it.

“Iran’s continued intransigence and the acceleration of its nuclear program will make it difficult for even the most forward-leaning negotiators to revive the agreement next year,” the Eurasia Group, a geopolitical risk advisory firm, said this past week in an assessment written by its Iran analysts.