United Nations -- The U.S. presented its case on Wednesday for the international community to punish Iran for its recent breaches of the 2015 nuclear deal, and offered incentives if Iran agrees to negotiate a new one. But as the 35-member Board of Governors of the International Atomic Energy Agency (IAEA) gathered in a boardroom in Vienna, Austria, for a closed-door meeting requested by the Trump administration, the battle lines were already drawn, and there was little hope of a unified stance.

The IAEA is the United Nations-backed global nuclear watchdog agency. It's responsible for monitoring and verifying Iran's compliance with the nuclear agreement. Wednesday's special session of its board was called by U.S. Ambassador to International Organizations in Vienna Jackie Wolcott to discuss the "concerning" report by the agency's director general, Yukiya Amano. Wolcott said, "the international community must hold the Iranian regime accountable."

The White House's case

"Iran's past pursuit of nuclear weapons – and its well-documented efforts to preserve and conceal information from its prior nuclear weaponization work – heightens the seriousness with which we and the international community should view these recent developments, and provides the historical context in which we must consider Iran's current actions and announcements," the U.S. envoy told the agency's Board of Governors Wednesday in Vienna.

U.S. Ambassador to the International Atomic Energy Agency (IAEA) Jackie Wolcott waits for the start of a board of governors meeting at the IAEA headquarters in Vienna, Austria, July 10, 2019. REUTERS

Wolcott warned the agency's delegates that, "Iran continues to make concerning statements regarding further escalatory steps it may soon take to advance its proliferation-sensitive nuclear activities."

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Until this year, the IAEA had verified Iran's compliance with the nuclear agreement since its implementation.

Mr. Trump had promised since before his election to pull the U.S. out of the deal, which he considers too generous to Tehran. He made good on that promise in May 2018 and unilaterally withdrew the U.S. from the agreement, and then imposed the harshest unilateral sanctions on Iran ever. He wants to negotiate a new deal that includes restrictions on Iran's ballistic missile program, its aid to proxy forces around the world, and a longer time frame before the deal sunsets. Iran has said flatly that it will not renegotiate the agreement it spent years hashing out with the U.S. and other world powers.

Wolcott made clear on Wednesday that the U.S. was offering Iran the potential of full diplomatic relations with Washington -- something Tehran hasn't had since 1979: "We call on Iran to reverse its recent nuclear steps and cease any plans for further advancements in the future. The United States has made clear that we are open to negotiation without preconditions, and that we are offering Iran the possibility of a full normalization of relations."

She underscored the Trump administration's call for a new deal: "We have been clear about the need for a negotiated solution that enduringly addresses the proliferation challenges presented by Iran's nuclear program. The JCPOA did not do so, nor did it address other aspects of Iran's destabilizing conduct. Iran's actions in the last two weeks further underscore the need for a comprehensive deal with Iran that addresses the totality of these concerns, ends the regime's destabilizing behaviors and sponsorship of terrorism, and fully reintegrates Iran into the international community."

Meanwhile, in Washington, President Trump said on Twitter Wednesday that sanctions against Iran would "soon be increased, substantially!"

Iran's decision last month to breach the terms of the deal -- which came after a year of warnings that they would take the action in response to the American withdrawal and sanctions -- prompted Walcott to call the IAEA meeting.

She pushed the other IAEA members of the agency's "shared and serious responsibility" to confront Iran, whose actions she called "a deliberate display of disregard for key limits the IAEA is entrusted to verify."

"There is no credible reason for Iran to expand its nuclear program, and there is no way to read this as anything other than a crude and transparent attempt to extort payments from the international community," she told the Board of Governors.

The agency's Board of Governors discussed two recent confidential reports by IAEA Director General Yukiya Amano on Iran's recent breaches, issued to Member States on 1 July and 8 July. The Board decided to make the reports public, after a U.S. request at the meeting.

IAEA's role in the nuclear deal

The 2015 deal put the IAEA in charge of verification and monitoring, but made it the U.N. Security Council's responsibility to resolve any disputes over compliance. The 15-member states of the Council can vote, if they believe Iran has breached the deal, to trigger a mechanism that would re-impose, or "snapback," the U.N. sanctions lifted in January 2016 as part of the agreement.

Those still-suspended U.N. sanctions are separate and apart from the punishments imposed by the Trump administration over the last year. The unilateral U.S. sanctions include measures that would penalize other nations -- including close European allies who signed the nuclear deal -- for any continued petroleum purchases from Iran. It was just that type of business the nuclear deal had permitted, bringing a much-needed promised lifeline for the cash-strapped Iranian regime.

The Europeans promised to create an international financial mechanism to get around the U.S. sanctions, to keep doing business with Tehran and effectively keep the nuclear deal alive. But with Washington keeping the pressure on its allies, progress has been slow, and that has left Iran frustrated and led to it breaching the deal.

No consensus

The closed-door meeting on Wednesday is unlikely to bring any unified stance.

Russia and China are board members of the IAEA and also permanent (veto-wielding) members of the U.N. Security Council. Their argument, and Iran's, is that the U.S., not Tehran, breached the 2015 agreement by pulling out and imposing new sanctions.

In a televised speech Wednesday, the spokesman for Iran's own Atomic Energy Organisation, Behrouz Kamalvandi, drove home that point.

"It was a huge mistake by the Americans to leave the deal... that has caused all the problems," he said, adding that Tehran believed the European nations had been given "enough time to salvage the pact," Kamalvandi said.

Irony of IAEA Board meeting on US request:

a. US abhors JCPOA, axed & violates it, and punishes all who observe it;

b. US has no standing to raise JCPOA issues;

c. Iran fully complied with JCPOA per 15 IAEA reports;

d. Iran's actions are lawful under para 36 of accord: pic.twitter.com/UOr316AZnx — Javad Zarif (@JZarif) July 10, 2019

Iran's Ambassador to the U.N. in Vienna Kazem Gharib Abadi said ahead of the meeting on Wednesday that it was "a sad irony that the same Regime which materially violated the JCPOA by withdrawing illegally and unilaterally from the deal… is expressing concern over the mere implementation of the same deal."

At the meeting, Gharib Abadi told board members: "The United States has not only prevented others from implementing their commitments fully, but also, including through revoking nuclear waivers, hampered Iran's implementation of its own commitments under the deal."

Explaining the recent breaches, he said Iran was "left with no choice but to exercise its rights under remedial provisions of the deal ... in order to re-establish the long missing balance in the reciprocal commitments of the JCPOA." He also addressed the allegations of developing weapons, saying that Iran's nuclear program is "exclusively for peaceful purposes."

After the meeting, an administration official indicated that the U.S. requested and the Board of Governors agreed to publish two recent IAEA reports on Iran's breaches.

Iran's breaches a threat?

The U.S. and many nuclear experts argue that with Iran now confirmed to be enriching uranium to higher purity, and its stockpile of enriched uranium growing, it could narrow the one-year window needed for the regime to have enough fissile material for a nuclear weapon.

Iran insists it has no interest in developing an atomic bomb and that its nuclear program is strictly for civilian purposes. The Trump administration and close ally Israel reject that claim, and say Iran has always wanted a nuclear weapon and will work secretly to develop one.

Israeli Ambassador to the U.N. Danny Danon said last week that Iran's increased enrichment levels were proof it "intends to develop a nuclear weapon."

But that is where Iran experts, policymakers, and the nations involved, disagree.

A "crisis of our own making"?

John D. Negroponte, former U.S. Director of National Intelligence and Ambassador to the U.N., told CBS News that "Iran's action would narrow the breakout time" for them to build a hypothetical atomic bomb.

But other experts believe Iran is breaching the agreement's terms just to pressure European nations into keeping the deal viable. The Europeans have also criticized Iran's recent actions, but they argue that the nuclear deal is still the only way to keep the Islamic Republic's nuclear ambitions in check without sparking what could be a complicated and costly war.

"This is entirely a crisis of our own making," said Gary Sick, a senior research scholar at Columbia University's Middle East Institute who served on the U.S. National Security Council.

"Iran, after a full year, decided that there was no advantage in continuing to remain in compliance with an agreement when they were getting nothing out of it," Sick, a retired U.S. Navy captain who served in the Persian Gulf, told CBS News.

"Iran is now taking advantage of a clause in the JCPOA (nuclear deal) that says they are entitled to exceed the limits of the agreement if any other country, i.e. the U.S., does not fulfil its own commitments (sanctions relief)," he said. "The object, admittedly risky, is to raise the potential costs of a breakdown for the other members -- especially the Europeans."