Since then, its relationship with Turkey, the sixth largest steel importer to the USA, the world's biggest steel importer overall, has deteriorated, prompting Ankara to send a delegation this week to Washington to meet with both the State and Treasury Departments. "Our relations with Turkey are not good at this time!" he wrote.
In an opinion piece in the New York Times, he warned the USA that Ankara had other alternatives as allies.
The lira's value fell about 13 percent against the dollar on Friday. It's down 40 percent this year against the dollar. The price of the lira dropped significantly immediately after he spoke. The weakened currency's value has helped increase inflation and anxious worldwide investors.
Iran has also suffered from a major tumbling of its currency this year partly over reimposition of U.S. sanctions after Trump abandoned a 2015 nuclear deal.
The president's characteristic defiance in the face of a shaky economy has further unnerved investors.
Erdogan has been putting pressure on the central bank not to raise interest rates in an attempt to help borrowers.
Erdogan signaled he was not looking to offer concessions to the United States, or financial markets.
"We will give our answer, by shifting to new markets, new partnerships and new alliances, to the one who waged an economic war against the entire world and also included our country", he said.
"If you have dollars, euros or gold under your pillow, go to banks to exchange them for Turkish lira".
Turkey was hit by a financial shockwave this week as its currency nosedived over concerns about the government's economic policies and a trade dispute with the United States.
"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", White House deputy press secretary Lindsay Walters said in a statement.
Stocks in the US and Europe skidded Friday as investors anxious about the financial stability of Turkey and how it might affect the global banking system.
After nearly 20 months in a Turkish jail, Mr Brunson was moved to house arrest last month by a court.
Andrew Craig Brunson, an evangelical pastor from Black Mountain, North Carolina, arrives at his house in Izmir, Turkey, Wednesday, July 25, 2018.
Mr Erdogan said although the nations had been allies for decades, Turkey "now has alternatives".
Erdogan on Friday held telephone talks with Russian President Vladimir Putin, discussing economic and trade issues as well as the Syria crisis.
Ankara had already taken measures to respond and would continue doing so, he added.