Mohammad Jamshidi, the Iranian president’s deputy chief of staff for political affairs, said in a post on Twitter on Friday that the president of the Islamic Republic had asserted that the first step for “engagement” is the release of the diplomat.
Assadi arrived in Iran on Friday. He was released after five years, following an Oman-brokered deal.
Earlier in the day, Iranian Foreign Minister Hossein Amir-Abdollahian tweeted that the “innocent” diplomat who was “illegally detained in Germany and Belgium for more than two years against international law” was freed after Muscat mediated a deal between Iran and Belgium to swap prisoners.
Iran released Belgian spy Olivier Vandecasteele, who was arrested on a visit to Iran in February 2022 and sentenced in January to 40 years in prison and 74 lashes on charges including espionage. 
In his tweet, Jamshidi said, “As Belgian officials used extreme language in parliament & media, on the phone they spoke of major engagement.”
Iran’s top human rights official also on Friday described Assadi’s detention in a Twitter post as “illegal”.
Assadi’s release is the “outcome of efforts by responsible authorities to defend the rights of their fellow citizens abroad,” said Kazem Gharibabadi, secretary of Iran’s High Council for Human Rights, promising to continue such efforts.
The Iranian administration’s spokesman Ali Bahadori Jahromi also tweeted on Friday that Assadi’s unlawful detention failed to impact the “steely will” of the “revolutionary diplomat.”
“Asadollah Assadi, our country’s diplomat, returned to his homeland after 5 years of illegal detention,” Bahadori Jahromi said.
He said Assadi’s detention was against international law as he was under mental and physical pressure.
The Iranian administration will employ all its capacities to preserve the rights of Iranians, he added. 
In June 2018, Belgian authorities said the country’s police had intercepted a car transporting homemade explosives, claiming the Iranian diplomat handed the material to two people in Belgium.
The diplomat was accused of plotting an attack against the anti-Iran Mujahedin-e-Khalq (MKO) terrorist outfit, a claim categorically dismissed by Iranian authorities.
A Belgian court then sentenced the diplomat, who serves as the third counselor at Iran’s Embassy in Vienna, to 20 years in prison.
MNA/PressTV