Esper explained that he would hold talks with his Turkish counterpart Khulosi Akar later, adding that on 26 June in Brussels he had informed him that Turkey could not have both the Russian S-400 and the F-35s advanced at the same time.
“We are aware of Turkey taking delivery of the S-400, our position regarding the F-35 has not changed and I will speak with my Turkish counterpart Minister Akar this afternoon,” Esper said at the Pentagon.
"There will be more to follow after this conversation," he added.
This comes as a senior Pentagon official told Al-Hurra that military relations with Turkey will witness "unprecedented spasm" on the backdrop of the S-400 deal.
For the first time, Pentagon commanders will review US air operations mechanisms based on the Turkish Incirlik base, adding that their future depends on the decision of President Donald Trump and the US State Department.
Source: Reuters, al-Hurra