TEHRAN(GN): Iran on Monday began enriching uranium to 4.5%, just breaking the limit set by its nuclear deal with world powers, while it is still seeking a way for Europe to help it bypass U.S. sanctions amid heightened tensions between Tehran and Washington.

The acknowledgement by the spokesman of the Atomic Energy Organization of Iran to The Associated Press shows that the Islamic Republic trying to increase pressure on those still in the 2015 nuclear deal. It also comes just days after Iran acknowledged breaking the 300-kilogram (661-pound) limit on its low-enriched uranium stockpile, another term of the accord.

The International Atomic Energy Agency, the U.N.’s nuclear watchdog, confirmed that Iran surpassed the enrichment threshold.

Experts warn that higher enrichment and a growing stockpile could begin to narrow the one-year window Iran would need to have enough material for an atomic weapon, something Iran denies it wants but the deal prevented.