Turkey and Iran have restarted a train service between Ankara and Tehran after a four-year hiatus, in a further blow to US sanctions.

The Trans Asia Express, carrying passengers and freight, left Tehran railway station for the Turkish capital on Wednesday during a ceremony attended by senior officials.

Head of the Islamic Republic of Iran Railways (IRIR) Saeed Rasouli flagged off the first train service which will run on a weekly basis every Wednesday.

According to Mehr news agency, the five-car train carrying 200 passengers took about 60 hours to arrive in Ankara on Saturday.

The decision to resume the service came in May after meetings between Iranian and Turkish officials. Trains between the eastern Turkish city of Van near the Iranian border and Tehran resumed in late June.

The new service involves two train travel segments and a ferry journey. The IRIR train leaving Tehran will have a layover in the Iranian city of Tabriz before heading to Lake Van in eastern Turkey.

Passengers will then ride a ferry across the lake before taking a train operated by Turkey’s state railway agency to Ankara.

The service marks yet another milestone in burgeoning trade ties between Iran and Turkey whose leaders have dismissed unilateral American sanctions on the Islamic Republic.

Washington has been tightening the screws on Tehran’s main source of income, aiming to cut Iran’s oil sales to zero, after President Donald Trump reimposed sanctions on the Islamic Republic in November.

According to data released by Tehran Chamber of Commerce Industries Mines and Agriculture on Monday, Turkey imported $2.2 billion worth of goods and services from Iran in the first quarter of the Iranian year which began in March.

The figure marked a five-fold jump compared to the similar period in 2018, it said.

Tehran and Ankara have repeatedly reiterated their resolve to increase annual trade to a target of 30 billion dollar, around triple current levels.

Earlier this year, Iranian deputy industry minister Mohsen Salehinia said Iran and Turkey were negotiating the possibility of setting up joint industrial parks.

“The Turks are demanding cheap Iranian energy for joint production and in case we manage to reach a conclusion with the ministry of energy, a joint town will be set up,” he told a news conference in Tehran.

On Sunday, President Hassan Rouhani of Iran and his Turkish counterpart Recep Tayyip Erdogan called for expansion of cooperation in various areas in a phone conversation.

Iran is one of the biggest oil suppliers for Turkey, which is almost completely reliant on imports to meet its energy needs. It also imports natural gas from Iran, the country’s second largest supplier after Russia.

Turkey has said it is looking into establishing new trade mechanisms with Iran, like the Instex system set up by European countries to avoid US sanctions reimposed last year on exports of Iranian oil.

President Erdogan has previously slammed the sanctions, saying they are destabilizing for the region.

His country is also facing US sanctions over Ankara’s purchase of Russian S-400 missile defense systems, which has seriously strained relations between the NATO allies.