Turkey’s central bank failed to halt the slide of the country’s lira currency on Monday as Turkish President Recep Tayyip Erdogan accused the United States of purposely trying to damage his country’s economy.

“We are together in NATO and then you seek to stab your strategic partner in the back. Can such a thing be accepted?” Erdogan said in the capital, Ankara.

The Turkish lira has plunged 40 percent this year, dropping 16 percent Friday and tumbling another seven percent Monday, trading at 6.9 to the dollar, up slightly from its low point.

The Turkish central bank said it would take “all necessary measures” to stabilize the country’s economy to make sure the banks have all the money they need. But world stock traders were dismayed the bank did not raise interest rates, which is what many economists believe is necessary to ease the crisis.

U.S. President Donald Trump doubled tariffs on Turkish steel and aluminum exports last Friday, in part a response to Turkey refusing to release American pastor Andrew Brunson, whom Turkey accuses of espionage.

Brunson has been detained under house arrest pending his trial. Trump has called the preacher’s detention a “total disgrace.”

Erdogan said Turkey is facing an “economic siege,” calling the decline of the lira an “attack against our country.” Yet he remained optimistic, saying “it is not at all like we sank and we are finished .The dynamics of the Turkish economy are solid, strong and sound and will continue to be so.”

On Sunday, speaking to political supporters Erdogan said “the aim of the operation is to make Turkey surrender in all areas, from finance to politics. We are once again facing a political, underhand[ed] plot. With God’s permission we will overcome this.”

“What is the reason for all this storm in a tea cup?” he said.”There is no economic reason for this … This is called carrying out an operation against Turkey.”

Erdogan renewed his call for Turks to sell dollars and buy lira to boost the currency, while telling business owners to not stockpile the American currency.

“I am specifically addressing our manufacturers: Do not rush to the banks to buy dollars,” he said. “Do not take a stance saying, ‘We are bankrupt, we are done, we should guarantee ourselves.’ If you do that, that would be wrong. You should know that to keep this nation standing is … also the manufacturers’ duty.”

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,” he said.

Erdogan has in recent years built closer ties with countries in Latin America, Africa, and Asia. “Some close the doors and some others open new ones,” he said.

He indicated Turkey’s relationship with Washington was imperiled.

“We can only say ‘goodbye’ to anyone who sacrifices its strategic partnership and a half-century alliance with a country of 81 million for the sake of relations with terror groups,” he said.”You dare to sacrifice 81-million Turks for a priest who is linked to terror groups?”

If convicted, Brunson, the pastor, faces a prison term of 35 years.