The U.S. is doubling tariffs on steel and aluminum imports from Turkey, President Trump announced Friday as he admitted the relationship with the NATO ally were strained.

“I have just authorized a doubling of Tariffs on Steel and Aluminum with respect to Turkey as their currency, the Turkish Lira, slides rapidly downward against our very strong Dollar! Aluminum will now be 20% and Steel 50%. Our relations with Turkey are not good at this time!” Trump tweeted.

The Trump administration has implemented broad-based tariffs of 25 percent tariff on steel and 10 percent tariff on aluminum. The lira continued to drop as Trump tweeted about raising the tariffs for Turkey, by as much as 14 percent against the U.S. dollar on Friday.

The tension between the U.S. and Turkey has increased as the Trump administration has called for the release of Andrew Brunson, a 50-year-old evangelical Christian pastor from North Carolina. He was detained in 2016 after he was blamed for assisting rebels in a coup. He has denied charges that say he engaged in espionage and collusion with terrorist organizations.

Last month, Brunson was released from prison and is currently on house arrest due to “health problems,” Turkey's official Anadolu news agency reported.

Trump warned that the U.S. would impose sanctions on Turkey if Brunson remains detained, and earlier this month imposed sanctions against two Turkish officials.