Turkish President Tayyip Erdogan was defiant in response, saying in a television interview that Turkey would not reconsider the decision to buy the Russian missile system, even if it meant giving up USA weapons.
Ankara signed an agreement with Moscow for the S-400 missile system in 2017. The missiles are not only incompatible with other weaponry the alliance uses, but also represent broader concerns that Turkey - the only predominantly Muslim country in North Atlantic Treaty Organisation and a key partner in Syria and other regional conflicts - is solidifying its turn away from the military bloc in favor of a partnership with Moscow.
On March 6, Turkish President Recep Tayyip Erdoğan told local television channels that not only will Turkey not back down from its S-400 plans, but it might seek the more advanced S-500 in the future.
Mr Erdogan would do well to heed the warning, as well as the possibility of U.S. sanctions.
"We will move toward a joint production".
"We signed a deal with Russian Federation for the purchase of S-400, and will start co-production".
However, the U.S.' unwillingness to share their technology drove Turkey toward Russia to purchase the Russian-made S-400 defense system. In January a year ago, Turkey awarded Eurosam, ASELSAN and Roketsan a contract for the definition study for the future Turkish Long-Range Air and Missile Defense System.
Turkey has invested more than US$1.25 billion in the stealth F-35 jet since its development phase began in 2002.
Turkey, the country with the longest land border with Syria which is considered to be a "failed state", a neighbor to the newly recovering Iraq, as well as having continental shelf problems with economically bankrupt Greece, still does not have an air defense system.
Turkey has particular ambitions for its neighbor Syria and the Kurdish fighters the USA backed as a principal strategy in fighting the Islamic State group on the ground.
Russian Federation has utilised the S-400 system in its military operations in Syria.
Trump has been largely silent on the issues affecting the Turkish-U.S. relationship. Deliveries were halted previous year by Congress.
The comments come as part of this week's back-and-forth between Ankara and Washington on the issue. But skepticism in Turkey toward American partners continues to grow.
Also not surprisingly, the USA offer came with a precondition that Turkey would have to back away from the S-400s deal with Russian Federation. "The answer is clear: Turkey can not trust and depend on the USA under these circumstances".