A Turkish appeals court upheld U.S. pastor Andrew Brunson’s house arrest Thursday despite threats of retaliation from the Trump administration, according to Bloomberg.

Brunson has lived in Istanbul for more than 20 years and held under house arrest for nearly two on espionage and terror-related charges.

His detention is the source of the latest feud between President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE and Turkish President Recep Tayyip Erdoğan. The White House said the charges against Brunson are baseless.

Last week, Trump said he would double tariffs on steel and aluminum from Turkey until Brunson is released. The administration has also sanctioned two top Turkish officials. Treasury Secretary Steven Mnuchin Steven Terner MnuchinOn The Money: Anxious Democrats push for vote on COVID-19 aid | Pelosi, Mnuchin ready to restart talks | Weekly jobless claims increase | Senate treads close to shutdown deadline Vulnerable Democrats tell Pelosi COVID-19 compromise 'essential' Pelosi asks panels to draft new COVID-19 relief measure MORE on Thursday threatened even more sanctions if Turkey does not release Brunson quickly.

Turkey has retaliated with its own tariffs on U.S. goods, including on cars and coal, and by threatening to boycott U.S. electronics.

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“Turkey has taken advantage of the United States for many years. They are now holding our wonderful Christian Pastor, who I must now ask to represent our Country as a great patriot hostage. We will pay nothing for the release of an innocent man, but we are cutting back on Turkey!” Trump tweeted Thursday.

Turkey has taken advantage of the United States for many years. They are now holding our wonderful Christian Pastor, who I must now ask to represent our Country as a great patriot hostage. We will pay nothing for the release of an innocent man, but we are cutting back on Turkey! — Donald J. Trump (@realDonaldTrump) August 16, 2018

The tariffs have taken their toll on the Turkish economy, with the lira dropping 20 percent in value last week, according to a CBS News report.