Last week, a top Pentagon official said the consequences would be “devastating” for Turkey’s joint F-35 fighter programme and its cooperation with NATO if the country went ahead with plans to buy the Russian anti-aircraft weapon system.
“There is an agreement. We have determination. It is out of the question to take a step back from it,” Erdogan told reporters in Istanbul on Tuesday.
He also said an offer from the United States to sell Patriot missiles to Turkey was not as good as the Russian offer.
Ties between the NATO allies have been strained over Ankara’s decision to buy the S-400 missile system, which Washington says could compromise its F-35 fighter jets that Ankara is also set to buy.
US officials urged Turkey to buy Patriot missiles rather than the S-400 from Moscow, arguing it is incompatible with NATO weapons systems.
Ankara responded saying it was the US refusal to sell Patriots to Turkey that led it to seek other vendors, adding Russia offered a better deal, including technology transfers.
Kathryn Wheelbarger, acting US assistant secretary of defence for international security affairs, said the planned S-400 purchase would damage Turkey’s ability to work with NATO.
She said the US administration, even if it does not want to punish Turkey for the purchase, could be forced to do so by a Congress unsympathetic to Ankara.
Turkey has suggested the two countries form a working group to assess the potential effect of the S-400s on F-35 aircraft, which was reportedly accepted by Washington.
Turkey plans to buy 100 US F-35s and some Turkish pilots have already started training with counterparts in the United States.
Erdogan said on Tuesday he told Washington that Ankara would take steps to buy the Patriots only if its conditions of delivery were as positive as Russia’s.
“But unfortunately we haven’t received a positive proposal from the American side on the subject of Patriots like the S400s from Russia,” he said.
The US has threatened to impose sanctions on Turkey if it goes through with the purchase of the Russian missile system, a move that would further damage Turkey’s economy.
Turkey’s currency the lira has declinedabout 14 percent this year in part because of concerns over the potential US sanctions.
Erdogan and US President Donald Trump are expected to meet on the sidelines of the G20 summit in Osaka, Japan, at the end of June.
In addition to the issue of the S-400, Turkish-US ties are already under strain over American support for a Syrian Kurdish militia in Syria – viewed as “terrorists” by Ankara.