Turkish President Recep Tayyip Erdogan addressed supporters Friday in the provincial city of Bayburt.
'Aluminum will now be 20 percent and Steel 50 percent. It came as a Turkish delegation returned from the United States, reporting no progress on negotiations involving a USA pastor imprisoned in Turkey. Hard currency debt issued by Turkish banks suffered similar falls.
The US president revealed the action on Friday as he noted how the Turkish lira "slides rapidly downward" against the "very strong" US dollar.
President Tayyip Erdogan of Turkey has told his citizens to sell their savings held in euros and dollars and buy lira in order to prop up the lira, citing an "economic war" after the country's currency has plummeted. On Friday, he said the country had to take steps in answer "to those who have waged an economic war against us".
The White House also cited currency movements in China last week when Trump called for a possible increase in tariff rates on Chinese imports. Turkey answered the March tariff announcement by placing its own tariffs on $267 million of USA goods.
The Turkish lira fell at least 13 percent Friday, as President Erdogan called for people to exchange their other forms of money to the lira. According to figures from the Turkish Government, for the period of 2002 to October 2017, Turkish direct investments in the United States reached $3.7 billion while US investments in Turkey amounted to $11.1 billion, second only to the Netherlands' 21.6 billion. Prices are already up 16 percent since previous year and this week's drop will make that worse.
Adding to investors' concerns, Erdogan pledged a continuation of his debt-fueled construction policy to boost the economy, which is blamed for Turkey's rampant inflation and has added to currency weakness. Investors in Turkey are also anxious about President Erdogan's interference in the country's central bank. Turkey has mostly done that to itself - until, that is, Trump started tweeting.
Meanwhile, markets are deeply concerned over the direction of economic policy under Erdogan, with inflation at almost 16 percent but the central bank reluctant to raise rates in response.
However, a report by Credit Suisse said Turkey remained a risk for Italy's biggest bank by assets as the depreciation of the lira could further hit its core capital - which came in lower than expected at the end of June.
An important emerging market, Turkey borders Iran, Iraq and Syria and has been mostly pro-Western for decades. "Look at what we were 16 years ago and look at us now", a reference to his terms as prime minister and president.
Independent analysts argue the central bank should instead raise rates to tame inflation and support the currency.
Erdogan said the two countries have been strategic partners and North Atlantic Treaty Organisation allies for six decades and reminded Washington that Turkey and the U.S. "stood shoulder to shoulder against common challenges during the Cold War and its aftermath".
Treasury and Finance Minister Berat Albayrak - who is Erdogan's son-in-law - was scheduled later on Friday to outline a "new economic model".