The world must return to a policy of “maximum pressure” against Iran to turn it into a more democratic country, US President-elect Donald Trump’s incoming Ukraine envoy Keith Kellogg tells an Iranian opposition event in Paris.

Trump has vowed to return to the policy he pursued in his previous term that sought to wreck Iran’s economy to force the country to negotiate a deal on its nuclear program, ballistic missile program and regional activities.

“These pressures are not just kinetic, just not military force, but they must be economic and diplomatic as well,” Retired Lieutenant-General Kellogg, who is set to serve as Trump’s special envoy for Ukraine and Russia, tells the audience at Paris-based Iranian opposition group National Council of Resistance of Iran (NCRI).

He says there is an opportunity “to change Iran for the better” but that this opportunity would not last forever.

“We must exploit the weakness we now see. The hope is there, so must too be the action.”

Iran’s foreign ministry says, “The hosting of a terrorist group by France is a clear example of support for terrorism and a violation of the French government’s international legal obligation to combat terrorism.”

Kellogg has previously spoken at NCRI events, most recently in November, but his presence in Paris, even if in a personal capacity, suggests the group has the ear of the new US administration.

Incoming US Secretary of State Marco Rubio has also spoken at NCRI events in the past.

The group has repeatedly called for the fall of the existing Iranian authorities, although it is unclear how much support it has within Iran.

The NCRI, the political arm of the People’s Mujahideen Organisation of Iran (PMOI), has held frequent rallies in the France, often attended by high profile former US, European and Arab officials critical of the Islamic Republic.