U.S. citizens traveling to Iran, particularly Iranian-Americans, risk arrest and detention in the Islamic republic, the U.S. State Department said in a travel warning Friday.

The notice, which was previously issued in August, updates the last warning specifically for dual citizens, a State Dept. spokesperson told The Foreign Desk.

“We just strengthened the language,” the spokesperson said.

This comes just days after five Americans, including four dual Iranian nationals, were released by Iran in a prisoner swap coinciding with the lifting of economic sanctions on Iran as the implementation of a deal to curb its nuclear program began.

The initial warning, according to the State Dept. aims to “reiterate and highlight the risk of arrest and detention of U.S. citizens.”

“Various elements in Iran remain hostile to the United States,” the statement said, noting that Iran has “continued to harass, arrest, and detain U.S. citizens, in particular dual nationals” since the nuclear deal was signed in July.

Reuters contributed to this report.