Iran’s Foreign Minister Mohammad Javad Zarif defended his 15-minute walk with US Secretary of State John Kerry during the nuclear negotiations in Geneva on Jan. 14. Pictures showing the two walking along the Rhone River became popular on social media. Many were surprised to see the foreign secretaries of these two nations taking a public walk and speaking so casually.

While riding a Tehran metro on Jan. 19 as part of a government effort to promote public transportation and reduce pollution, Zarif dismissed criticism of his walk with Kerry, saying that his critics “want to use it as a partisan issue.” Zarif said that the negotiations in Geneva were intense, and the two decided to step out for fresh air as the hotel did not have a garden. He added that the act was “natural,” given the long hours of the meetings with no breaks other than for prayers.

To his critics, Zarif said, “I’ve said many times that the negotiations are a national movement, not a partisan movement,” adding, “I expect our friends not to sacrifice national interests for partisan considerations.”

Iranian critics of Zarif’s walk with Kerry were not placated by Zarif’s response. The harshest statements came from the head of Basij Organization Mohammad Reza Naghdi, who said, “Showing intimacy with the enemy of humanity is completely wrong.” He added, “Zarif walking with the US secretary of state was trampling the blood of martyrs.”