UNITED NATIONS (Reuters) - Turkish President Tayyip Erdogan said on Tuesday that his country could not remain silent over the use of sanctions as weapons while it is in a bitter standoff with the United States over the fate of an American evangelical Christian pastor detained by Ankara.

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The United States has called for the release of pastor Andrew Brunson, who was moved to house arrest in July after being detained for 21 months. If found guilty, he could be jailed for up to 35 years. He denies the charges.

Turkey says the United States should respect the legal process for the pastor, whose trial in Turkey on terrorism charges has infuriated U.S. President Donald Trump.

“None of us can remain silent to the arbitrary cancellation of commercial agreements and the use of economic sanctions as weapons,” Erdogan said in a speech to the United Nations General Assembly.

In August, Trump authorized a doubling of duties on aluminum and steel imported from Turkey. Turkey responded in kind, raising tariffs on U.S. cars, alcohol and tobacco imports.

The lira has lost nearly 40 percent of its value against the dollar this year on concerns about Erdogan’s grip on monetary policy and the diplomatic dispute between Ankara and Washington.

The Trump administration has also imposed sanctions on two top officials in Erdogan’s cabinet as part of its efforts to pressure Turkey into freeing Brunson.

“Today, some countries are persistently trying to create chaos. We are in favor of solving our problems through conducting a constructive dialogue on equal terms,” Erdogan said.

However, the Turkish Lira firmed slightly on Tuesday as investors weighed up the prospect of an improvement in Turkey-U.S. ties after U.S. Secretary of State Mike Pompeo said he expected talks this week over Brunson’s fate.

Erdogan’s communication adviser Fahrettin Altun posted on Twitter a picture of Erdogan and Trump shaking hands and smiling at the United Nations.

Ankara and Washington are also at odds over diverging interests in Syria, where Washington supports Kurdish rebels whom Turkey regards as terrorists.

“Those who equip terrorists with tens of thousands of trucks and thousands of cargo planes loaded with arms for the sake of their tactical interests will most definitely feel sorrow in the future,” Erdogan said.

Washington has expressed concern that NATO member Turkey’s planned deployment of the Russian-made S-400 could risk the security of some U.S.-made weapons and other technology used by Turkey, including the F-35 jet.