Washington (CNN) President Donald Trump said Friday he is greenlighting a doubling of steel and aluminum tariffs on Turkey and warned that US relations with the country "are not good at this time."

The moves stem from Trump's frustration over a detained American pastor held by Turkey on what US officials say are bogus charges, two sources with knowledge of the President's mind-set tell CNN.

"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!" the President tweeted.

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!

In a statement, deputy White House press secretary Lindsay Walters said, "Section 232 tariffs are imposed on imports from particular countries whose exports threaten to impair national security as defined in Section 232, independent of negotiations on trade or any other matter."

Walters did not offer any explanation as to how US national security is threatened by steel and aluminum imports from Turkey, which hosts a major US military base.

Trump's announcement Friday could further escalate tensions with Turkey, continuing the steady downward spiral of US relations with Ankara, which has been driven by a slew of factors. Andrew Brunson , a 50-year-old evangelical Presbyterian from North Carolina who has lived in Turkey for more than 23 years, has become the face of the US-Turkey friction

Turkey has accused Brunson of helping to plot a 2016 coup attempt against Turkish President Recep Tayyip Erdogan. US officials maintain there is no credible evidence against Brunson, and the Trump administration has negotiated for weeks to secure his release.

Waging economic war

Erdogan alluded Friday to "those who wage economic war on us" and told Turks to exchange their dollars and euros for Turkish lira.

Turkish presidential spokesman Ibrahim Kalin took to twitter Friday to voice Turkey's strong will against any threats.

"No threat, blackmail or operation can discourage the will of Turkey," he wrote on his official Twitter account hours after Trump announced the additional tariffs.

Attached to the tweet was an image and quote from Erdogan saying those who assumed that Turkey would bow down before economic manipulations do not know the Turkish nation.

Kalin also said those who thought everything was over after the defeated coup in July 2016 were wrong then and will be wrong again, adding, "Turkey will win this fight as well."

"This is just another example of the almost Shakespearian drama that has unfolded between US and Turkey since 2016," said Nick Heras, a Middle East expert at the Center for a New American Security.

"There is a real sentiment within the pro-Erdogan camp that the US was covertly a backer of the 2016 coup against Erdogan."

Earlier this month, the United States slapped sanctions against Turkey's ministers of justice and interior in response to Brunson's detention. Since then, talks over Brunson's release have broken down. A week ago, Turkey ordered that the assets of the US "justice and interior" secretaries would be frozen.

National Security Council and State Department officials continued to go back and forth with their Turkish counterparts this week, but nothing has been resolved, an official told CNN. Before the President's trip to Europe last month, officials said they believed they were close to securing Brunson's release.

'Innocent man of faith'

"This innocent man of faith should be released immediately!" Trump wrote on Twitter late last month.

Pastor Andrew Brunson, a fine gentleman and Christian leader in the United States, is on trial and being persecuted in Turkey for no reason. They call him a Spy, but I am more a Spy than he is. Hopefully he will be allowed to come home to his beautiful family where he belongs! — Donald J. Trump (@realDonaldTrump) April 18, 2018

Also in July, Brunson was moved from jail to house arrest after being held for more than a year and a half.

Trump and Vice President Mike Pence have had conversations with officials in the Turkish government regarding Brunson, according to an administration official, and Trump and Erodgan discussed Brunson during a call in mid-June. The White House never issued a readout of the call but confirmed it after the Turkish government disclosed details. It's unclear if the two leaders have spoken since.

On Thursday, State Department spokeswoman Heather Nauert said US officials had held a "wide-ranging conversation" with their Turkish counterparts this week.

"We made it clear that Pastor Brunson needs to be returned home. ... The progress that we want to be made is to have Pastor Brunson return home. And I'll leave it at that," she said.

Trump's tariff announcement comes in the midst of a currency slump in Turkey. The value of the lira has plummeted against the dollar, which Trump pointed out in his tweet on Friday, saying the Turkish currency is sliding "rapidly downward against our very strong Dollar!"

Escalating tensions

Tensions in the Turkey-US relationship have been steadily ratcheting up, even as the NATO allies cooperate on other fronts, perhaps most importantly coordinating over the US air base in Incirlik, Turkey.

Pentagon spokesman Eric Pahon said work at the base continues and that the US-Turkey military relationship remains intact.

"We continue to carry out our important mission at Incirlik, and maintain a strong, mil-to-mil relationship with our Turkish counterparts," Pahon told CNN. "We continue to cooperate on key regional defense issues with our NATO ally."

Heras, the Mideast expert, said, "Incirlik has always sort of been entangled in this situation, viewed by Erdogan backers and Erdogan himself as a chip in a game. At the officer-to-officer level ... relationships are as good as they can be given the circumstances. However, the politics between the US, under two administrations, and the Erdogan government are becoming more and more poisonous -- and this is where it becomes more dangerous."

Heras said any Turkish action against US service members based at Incirlik or a concerted effort to halt counter-ISIS operations from there would be the type of hand Erdogan would play only if he "decides the situation has gone so far that he needs to throw a big move in Trump's face."

Other issues have eroded support for Turkey in the United States. Erdogan's increasingly authoritarian tendencies and suspected human rights abuses have alienated lawmakers in Congress.

Frank words from Erdogan

Erdogan, in an op-ed dated Friday in The New York Times , decried US actions toward Turkey and warned that the future of their decades-long "shoulder to shoulder" alliance could be in peril.

He argued that Turkey has come to the aid of the United States over the years, citing deployment of its troops during the Korean War and the NATO-led fight against terror in Afghanistan.

But in recent years, he said, "our partnership has been tested by disagreements."

Erdogan criticized the United States over its actions in the Brunson affair, its reaction to the coup attempt two years ago and its alliance with the People's Protection Units, or the YPG, the fighting group in Syria that the Turkish leader asserts is a branch of the Kurdistan Workers' Party, labeled a terror group by the United States.

"Unless the United States starts respecting Turkey's sovereignty and proves that it understands the dangers that our nation faces, our partnership could be in jeopardy," Erdogan said.

"Before it is too late, Washington must give up the misguided notion that our relationship can be asymmetrical and come to terms with the fact that Turkey has alternatives. Failure to reverse this trend of unilateralism and disrespect will require us to start looking for new friends and allies."

The Turkish leader's cooperation with Iran and Russia in Syria has also left US foreign policy officials uneasy, as has his decision to buy Russia's surface-to-air S-400 missiles, which are not compatible with NATO allies' systems.

Erdogan has been deeply angry about the slow US response to the coup attempt against him. Turkey has accused Fethullah Gulen , a cleric who lives in exile in Pennsylvania, in the attempt, and it has repeatedly tried to get him back and put him on trial.

US support for Kurds in Syria who are combating ISIS has also deeply angered Erdogan. The Syrian Kurdish group the YPG is a core element of the US-backed alliance fighting the militants, but Erdogan sees it as a security threat. In 2017, the Turkish leader went so far as to threaten the United States with an "Ottoman slap" if it tried to block a Turkish military incursion into Syria.

Turkey has also been concerned about the fallout of Trump's decision to leave the Iran nuclear deal and to sanction those who continue to do business with Tehran. A significant portion of Turkey's oil imports come from Iran. When the United States reimposes sanctions on Iranian energy exports in November, Turkey's already suffering economy could take another blow.