Everything went according to plan despite Washington's veiled and open threats and warnings. Russian planes carrying the first batch of equipment landed at MürtedAir Base outside the capital Ankara. The missiles will reportedly be shipped to Turkey by sea in coming days. According to sources, it could take up to two months to install the defense system. In other words, the S-400 system will start protecting Turkish airspace starting in September.

The United States is unhappy with this development. U.S. officials had shared their concerns with their Turkish counterparts in the past. Briefly, Washington threatened to impose certain sanctions on Turkey and remove its ally from the F-35 program if it deployed the S-400 system. Reactions to the S-400 delivery echoed the same sentiment. Senator Chris van Hollen argued that Turkey had made a poor decision, as Senator Ron Johnson announced Turkey's removal from the F-35 program. The House Committee on Foreign Affairs issued a similar statement last week.

Acting Defense Secretary Mark Esper noted that Washington's position on the F-35 program remained unaltered before a phone call with his Turkish counterpart Hulusi Akar. After the 30-minute call, Ankara issued a readout stressing that Turkey's move to purchase the S-400 system was a necessity rather than a choice. The Turkish side added that negotiations were underway on the Patriot deal. The United States, however, did not issue a formal statement on the phone call. We know that the Pentagon intended to hold a press briefing after the S-400 delivery, which was postponed twice on Friday. That briefing will reportedly take place today. Some sources maintain that the State Department influenced that decision, which suggests that Washington would like to choose its words carefully when it announces its official policy.

How will the United States respond? It will remove Turkey from the F-35 program, although the Turks are a key partner and have already invested $1.4 billion in that project. Second, Washington will impose Countering America's Adversaries Through Sanctions Act (CAATSA) sanctions on Turkey, which Trump must do, but can decide how. At last month's G20 summit in Japan, the U.S. president told reporters that Turkey had been treated unfairly on the S-400 deal. His remarks strengthened Turkey's hand and signaled that Trump could implement CAATSA sanctions in a reluctant and limited manner.

Critics of Turkey's S-400 procurement must understand that the Turkish-Russian agreement is a matter of national sovereignty. Turkey already demonstrated its commitment to its independence by refusing to walk back the S-400 agreement. Having failed to buy the Patriot system from the United States in the past, Turkey established that it wants to protect its airspace. As such, Turkey's independence must not be tested.

Last but not least, Turkey's neighborhood could set the stage for surprise developments. Turkey might move on other vital issues to demonstrate its national sovereignty and independence. Perhaps the S-400 delivery and the F-35 dispute will be overshadowed by other developments. How do I know? The Turkish readout of Defense Minister Akar's phone call with Esper included a seemingly unrelated sentence. The Turks maintained that the U.S. had agreed to urgently send a formal delegation to discuss the proposed safe zone in Syria. The U.S. delegation's immediate deployment to Turkey and Ankara's emphasis on the urgency of their arrival were worth noting.