The US State Department on Friday warned its citizens, particularly Iranian-Americans, to carefully consider the risks of travelling to Iran, saying they could face arrest and detention there.
The warning comes after the US-Iranian prisoner swap in which five American citizens, including four dual Iranian nationals, were freed. The move coincided with the lifting of economic sanctions on Iran as the implementation of a deal to curb its nuclear program began.
The department says those who have dual citizenship are especially at risk.
The warning aims to "reiterate and highlight the risk of arrest and detention of US citizens, particularly dual national Iranian-Americans, in Iran," the State Department said.
"Various elements in Iran remain hostile to the United States," it said, adding that Iran has "continued to harass, arrest, and detain US citizens, in particular dual nationals" since the nuclear deal was signed in July.
In his first appearance since returning to the United States, one of the prisoners freed in the swap, Washington Post reporter Jason Rezaian, thanked US Secretary of State John Kerry on Thursday for negotiating his release after he spent 18 months in an Iranian jail.