German citizens are being asked to leave Iran and refrain from travelling to the country due to concerns about potential retaliatory actions by Tehran regarding sanctions, the Federal Foreign Office said late Thursday.

Germany along with France and the United Kingdom on Thursday triggered the process to reimpose sanctions on Iran at the United Nations Security Council. Those sanctions were lifted in 2015 under the Joint Comprehensive Plan of Action (JCPOA) in exchange for Iran agreeing to keep its nuclear program strictly peaceful.

“Since Iranian government officials have repeatedly threatened consequences in the past, it cannot be ruled out that German interests and nationals will be affected by countermeasures in Iran,” the Foreign Office said in a statement on its website.

The three countries, known as the E3, said they had tried to bring Tehran back to the negotiating table over its nuclear program, but that Iran keeps violating the commitments under the 2015 nuclear deal.

Iran has been increasingly breaching the deal since the United States under Donald Trump withdrew from the JCPOA in 2018.

Iran’s foreign ministry condemned the move by the E3 countries, calling it a “provocative and unnecessary escalation.” It promised “appropriate responses,” without going into detail.

The U.N. sanctions in place before the 2015 deal include a conventional arms embargo, restrictions on ballistic missile development, asset freezes, travel bans and a ban on producing nuclear-related technology.