Iran says it has again breached the terms of the 2015 nuclear deal, enriching uranium to more than 3.67% purity.

It's Iran's second breach of the deal's terms, and comes after President Trump warned the country to "be very careful."

Tehran wants Europe to help it get around U.S. sanctions, but Europe thus far seems to be siding with the U.S.

Iran says if the EU fails to find a way to keep the nuclear deal viable within two months, it will do something "somehow stunning."

Iran remains open to diplomacy to save its 2015 nuclear deal with world powers but has "no hope" in the international community, the country's Foreign Ministry spokesman said Monday as the Islamic Republic broke the limit the agreement had placed on its enrichment of uranium.

The future of the accord that President Trump unilaterally pulled the U.S. from a year ago remains in question. While Iran's recent measures to increase enrichment and break its low-enriched uranium stockpile limit could be easily reversed, Europe has struggled to respond, even after getting a 60-day warning that the increase was coming.

Iran wants Europe to come up with a way to help it sell its crude oil abroad and get around U.S. sanctions, but Europe has yet to do so.

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Meanwhile, experts fear a miscalculation in the crisis could explode into open conflict, as Mr. Trump already has nearly bombed Iran over Tehran shooting down a U.S. military surveillance drone.

Trump: "Iran better be careful"

Mr. Trump warned Tehran on Sunday that "Iran better be careful." He didn't elaborate on what actions the U.S. might consider, but told reporters: "Iran's doing a lot of bad things."

Iranian Foreign Ministry spokesman Abbas Mousavi said he had no information on how far Iran had taken its enrichment, though a top aide to Supreme Leader Ayatollah Ali Khamenei previously suggested that Tehran had a need for 5%-enriched uranium. Iran's state-controlled media said uranium was being enriched to 4.5% as of Monday.

Under the nuclear deal, the cap for enrichment was set at 3.67%, a percentage closely monitored by inspectors from the International Atomic Energy Agency, the U.N.'s nuclear watchdog.

Agency inspectors verified Monday that Iran was enriching uranium above the cap, IAEA spokesperson Fredrik Dahl told CBS News' Pamela Falk.

Enriched uranium at the 3.67% level is enough for peaceful pursuits but is far below weapons-grade levels of 90%.

The decision to ramp up uranium enrichment came less than a week after Iran acknowledged breaking the deal's 300-kilogram (661-pound) limit on its low-enriched uranium stockpile. Experts warn higher enrichment and a growing stockpile could begin to narrow the one-year window Iran would need to have enough material for an atomic bomb, something Iran denies it wants but the deal prevented.

Iran warns of something "stunning"

Mousavi on Monday said Iran appreciated the efforts of some nations to save the deal, but offered a jaded tone on whether Tehran trusted anyone in the negotiations.

"We have no hope nor trust in anyone nor any country but the door of diplomacy is open," Mousavi said.

He also gave a sharp, yet unelaborated warning to Europe about another 60-day deadline Iran set Sunday. That deadline will come Sept. 5.

"If the remaining countries in the deal, especially the Europeans, do not fulfill their commitments seriously, and not do anything more than talk, Iran's third step will be harder, more steadfast and somehow stunning," he said.

Behrouz Kamalvandi, a spokesman for Iran's nuclear agency, separately hinted in a state television interview aired Monday that the country might consider going to 20% enrichment or higher as its third step, if the material is needed. That would worry nuclear nonproliferation experts, as 20% is a short technical step away from reaching weapons-grade levels of 90%. Behrouz also suggested using new or more centrifuges, which are limited by the deal.

Iran calls tanker seizure "piracy"

Meanwhile, Mousavi called the seizure of an Iranian supertanker off the coast of Gibraltar "piracy," but stopped short of suggesting Iran take actions against ships transiting through the Strait of Hormuz, the narrow mouth of the Persian Gulf through which 20% of all crude oil passes.

A European security boat approaches supertanker Grace 1 off the coast of Gibraltar, July 6, 2019. Getty

Mousavi said he didn't know where an Iranian supertanker was heading when it was seized off the coast of Gibraltar. Authorities there say they seized the Grace 1, believed to be carrying over 2 million barrels of oil, over European Union sanctions on Syria — though Spain said the seizure came at the request of the U.S.

Hard-liners in Iran have demanded a British oil tanker be seized in response. A lawmaker also has suggested Iran charge ships moving through the Strait of Hormuz, something Mousavi dismissed while insisting Iran's right to patrol the waters off their coast.

Iran is neither a member of the EU nor subject to any European oil embargo. Last I checked, EU was against extraterritoriality. UK's unlawful seizure of a tanker with Iranian oil on behalf of #B_Team is piracy, pure and simple. It sets a dangerous precedent and must end now. — Javad Zarif (@JZarif) July 8, 2019

"We are responsible for maritime protection of the Persian Gulf and the Strait of Hormuz. This is our region. This is our gulf," he said, reiterating Iran's longtime stance. "This is our innate duty to secure this region and sustain its security. Countries that claim from thousands of miles from here that they should guarantee the maritime security here are speaking exaggeratedly."