then why do you think Iran is currently negotiating with the E3 to give them concessions to agree to delay the snapback deadline
Iran is not negotiating with Europeans to "delay SNAPBACK implementation"... that doesn't exist. If SNAPBACK is truly activated by the UN Security Council and international law, it makes no difference (to Iran) whether it is activated in July or October (which is the last month to activate it, after which it can no longer be enforced). Iran is negotiating with Europeans to NOT ATTEMPT TO ACTIVATE SNAPBACK, as this would require more "stress" in international negotiations and more concessions that Iran would have to make to Russia and China in the long term, diminishing its "outside the system status QUO” that Iran wants to maintain.
However, once the Europeans (controlled by Zionism) try to activate SNAPBACK, then its activation is not so easy because the Europeans violated the agreement as in the case of INSTEX (financial compensation system that didn't work) and the JCPO itself provides that participants who violated the agreement CANNOT ACTIVATE SNAPBACK:
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Paragraphs 26-27 JCPO (Participants' Commitments)
-All signatories must fulfill their obligations (EU: economic timeout; US: suspend assessments; Iran: nuclear limits).
- If a country fails to comply,
Iran can reduce its own obligations*
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*(as it did after the US withdrawal in 2018).
In an attempt to activate snapback, the E3s would notify the Council. Within 30 days, a resolution would be required to maintain sanctions relief.
If any permanent member vetoes this resolution—or if it fails to receive nine votes in favor—SNAPBACK occurs. However, if the Council believes the E3s have no legitimate right to activate it(because they violate it), they could vote against their own resolution or support another text that formally rejects the request. It's not as simple as it seems, and that's why the US action (in 2020) to activate SNAPBACK failed to pass the UNSC.