My last article focused on Turkish President Recep Tayyip Erdogan’s Nov. 13 visit to Washington as a whole. This article will focus on the most important issue discussed during that visit — Ankara’s purchase of Russia’s S-400 air defense system — because it has the potential to spoil many aspects of Turkish-US relations. Moscow was not part of the talks in Washington, but the outcome directly affects Turkish-Russian relations. When the S-400 issue came up in the early 2010s between Turkey and the US, Washington was furiously opposed to it, on the grounds that the air defense system could identify weaknesses in NATO’s new-generation F-35 fighters, and because purchasing Russian equipment would be a loss for member states’ industry. At the time, Erdogan chose to use megaphone diplomacy with the US, addressing the NATO ally with words that made domestic audiences in Turkey proud of their president. But this antagonized decision-makers in Washington. He was confident that “his good friend,” US President Donald Trump, would silence those who were opposed to Turkey’s policy on this issue, and would find a way out of the deadlock. This expectation is now being tarnished. The background of the S-400 affair shows that Erdogan was originally right in his approach. At the height of Middle Eastern crises, Turkey needed a reliable air defense system. Some NATO countries agreed to help by temporarily deploying their US-made patriot batteries in Turkey, but they withdrew them before the threat was over. Therefore, Ankara decided that it would not rely on the goodwill of other countries. It opened a tender to acquire an air defense system. Several countries submitted offers. The Russian bid was $8.4 billion, the US bid was $4.6 billion, the Italian-French bid was $4.4 billion, and the Chinese bid was $3.44 billion. Turkey could not take the Chinese offer because of US sanctions. Initially the Russian bid was the highest, but by bargaining a slightly different format, it was agreed for $2.5 billion. In addition, a new version of the S-400 was scheduled to be manufactured in Turkey under the co-production formula. In light of this backdrop, Erdogan thought he could use his close relations with Trump to persuade various departments in Washington that Turkey was right in what it was doing. But Erdogan did not take into account the importance of the separation of powers in the US, and the power of the legislative to limit the actions of the president. Both leaders did their best to overcome the difficulty. The S-400 is not interoperable with the NATO Air Defense Ground Environment (NADGE), and the deal drives a wedge between Turkey and other NATO allies. Yasar Yakis The S-400 is not interoperable with the NATO Air Defense Ground Environment (NADGE), and the deal drives a wedge between Turkey and other NATO allies. The US Congress is adamant on imposing sanctions if the S-400 is deployed in Turkey. The Washington Post reported that Trump had sent an ultimatum-like letter shortly before his meeting with Erdogan, telling him that Turkey would face sanctions if it did not refrain from deploying the S-400 and promise that it would not buy other Russian weapons. Trump added that the US would like to send observers to Turkey to verify whether the S-400 has been deployed. After returning from Washington, Erdogan said in a meeting of the parliamentary group of his ruling AK Party that he had explained the background to Trump, and that the latter understood the reasons behind Turkey’s attitude, but because of the impeachment process and next year’s US presidential elections, he had to move cautiously. Erdogan also said he explained to Trump that it would not be possible for Ankara to give up the S-400, and that insisting on this would amount to interference in Turkey’s sovereign right to acquire any air defense system that it wishes. The two leaders chose the right way in this difficult atmosphere, and decided to refer the issue to a committee that includes the foreign ministers of both countries, with the participation of defense and intelligence experts. They will meet on Dec. 4 on the sidelines of the NATO Summit in London. A miracle on this complicated problem is unlikely in the foreseeable future. Moscow will follow developments with the utmost attention. Since Turkey has committed itself to paying for the system, there is no economic loss for Russia, even if, due to strong US pressure, Ankara refrains from deploying it. But Turkish-Russian relations will emerge bruised from this clash. In light of this background, the deployment of the S-400 may be postponed until the impeachment and election processes are over. • Yasar Yakis is a former foreign minister of Turkey and founding member of the ruling AK Party. Twitter: @yakis_yasar Disclaimer: Views expressed by writers in this section are their own and do not necessarily reflect Arab News" point-of-view