Turkey says it will honor the deal to purchase S-400 defense systems from Russia after US senators threatened to ban the transfer of F-35 fighter jets if Ankara goes ahead with the plan. 

AVA- Speaking in Antalya at a joint news conference with Russian counterpart Sergei Lavrov Friday, Turkish Foreign Minister Mevlut Cavusoglu said Moscow and Ankara were discussing delivery times.
Cavusoglu also said Turkey has met its obligations to be part of the F-35 fighter aircraft plan but the US is making contradictory statements over the program.
His remarks came after four US senators on Thursday introduced a bipartisan bill to prohibit the transfer of F-35s to Turkey unless Ankara stops taking delivery of the S-400 system. 
The bill introduced by Democratic Sen. Jeanne Shaheen and Republican Sen. James Lankford will add to growing US pressure on Turkey to turn away from the Russia deal.
The United States and other NATO allies who own F-35 fighter jets fear the radar on the Russian S-400 missile system will learn how to spot and track the F-35, making it less able to evade Russian weapons in the future.
Shaheen, a member of the Senate’s foreign relations and armed services committees, says Ankara’s purchase of Russia’s S-400 missile defense system would give Moscow access to the US aircraft and technology in Turkey and that “is a serious national and global security risk.”
In a bid to prevent the S-400 system from being operated on the NATO soil, the US has offered Turkey the more expensive Patriot anti-missile system at a discount that expires at the end of March, but on condition that Ankara drop its plans to buy the S-400.
So far Ankara has not shown any willingness to reverse the S-400 purchase.
Turkish President Recep Tayyip Erdogan said earlier this month that his country will not go back on its agreement to buy S-400 systems from Russia, despite pressures from the United States.
"It's done," Erdogan said in an interview with broadcaster Kanal 24 on March 6, stressing that "there can never be a turning back".
"This would not be ethical, it would be immoral. Nobody should ask us to lick up what we spat," he said.