Differing interpretations over whether Iran can conduct research on more advanced centrifuges under a nuclear deal signed last month is among the key issues to be resolved for the agreement to enter into force, nonproliferation experts suggested Sunday.

Technical experts from Iran and six world powers are scheduled to resume talks on implementing the Joint Plan of Action in Geneva on Monday, December 30.

“What may be happening here is that Iran has notified the P5+1 that it plans to install additional IR-2M centrifuges at the Pilot Fuel Enrichment Facility at Natanz where it has historically conducted centrifuge research and development,” Jofi Joseph, a former US official who worked on Iran nuclear issues, told Al-Monitor.

“Throughout the diplomatic talks that culminated in the Geneva agreement, Iran has insisted upon the right to continue unfettered research and development for its centrifuge program that should fall outside any limits on its centrifuges producing enriched uranium,” said Joseph, who recently wrote about potential pitfalls to the Nov. 24 interim Iran nuclear deal at the Atlantic Council website. “The P5+1 always pushed back, seeking to protect against a scenario where Iran could use this R&D loophole as a back door to expand its centrifuge capacity even as a [confidence building measure] CBM agreement took effect.”