Erdogan calls US sanctions 'attack on sovereignty'
The United States made good on months of threats to punish Turkey for buying the S-400 system under a 2017 law known as CAATSA, which aims to limit Russia's military influence and punish it for its behaviour abroad.
The sanctions were lighter than feared, but Erdogan noted that they had never before been used against a fellow member of NATO.
"Sanctions are imposed on our country, a NATO member. What kind of an alliance is this?" Erdogan asked during a televised speech in Ankara.
"This decision is an open attack on our sovereignty," he added.
Washington had already punished Ankara in July by barring it from developing parts for and acquiring America's next-generation F-35 fighter jets.
This week's punitive measures included a ban on all US export licences and loan credits for Turkey's military procurement agency.
Its president Ismail Demir and three other executives were also barred from travel or holding assets in the US.
The State Department said the sanctions "are not intended to undermine the military capabilities or combat readiness of Turkey... but rather to impose costs on Russia in response to its wide range of malign activities".
But in his first public comments about the sanctions, Erdogan called them unjust.
He repeated Turkey's claim that Washington would not sell the US equivalent to the S-400, the Patriot, to Ankara.
US officials say Turkey was offered the system, but that negotiations broke down after Ankara demanded to also obtain proprietary production and operations data about the Patriots.
"The more Turkey grows, the more Turkey inches closer to its goals, the more it stands up for its sovereign rights, the more it is subjected to attacks," Erdogan said.
"Because we met our needs somewhere else, they pulled the sanctions trigger."
Washington says the S-400 system would put the security of US military technology and personnel at risk, as well as providing funds to the Russian defence industry.
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Erdogan said Turkey offered to resolve the issue through diplomacy and would now redouble its efforts to developing its own arsenal.
"To make our defence industry independent, we will work twice as hard, we will accelerate our defence industry agency's projects, we will give more support to our defence-related companies," he said.
The sanctions are the latest thorn in US-Turkey relations, with the NATO allies at loggerheads over Syria, Libya and the eastern Mediterranean Sea.
But with a month before the swearing in of President-elect Joe Biden, who once described Erdogan as an "autocrat", Ankara's language has generally softened towards Washington.