Turkey's plans to buy the S-400 missile defense system from Russia has sparked unprecedented tensions between Turkey and the U.S. Neither side will back off, and the prospect of an irreparable rupture in relations is looming. Yet the current crisis is not the source, but the result of the widening divergence between the two countries.

Along with strategic disputes, Turkey's growing corruption is imperiling relations on an even larger scale. Corruption is omnipresent, but it didn’t start with Recip Tayyip Erdoğan, although Erdoğan has institutionalized corruption in Turkey by creating a hierarchical network encompassing many fields of economic activity. Over time, this network has begun to define how Turkey engages with other countries.

Erdoğan's vast network emerged in 2013 when a well-documented investigation by the police exposed a gigantic bribery and money laundering ring involved in illegal gold transfers to Iran. The ring included  ministers in Erdogan’s cabinet. Reza Zarrab, a Turkish businessman of Iranian descent, was arrested for being the ringleader. When the investigation focused on his own son, Erdoğan claimed that it was a coup against his government and started a crusade against the rule of law and the free media in order to protect himself and his family from facing trial. Zarrab was released after two months without any charges.

In March 2016, Reza Zarrab was arrested in the U.S., this time for helping Iran evade U.S. sanctions. He pleaded guilty and implicated Erdoğan in the scheme. The deputy chief executive officer of Turkey’s state-owned Halkbank, was also found guilty on related charges of conspiring to violate U.S. sanctions law, raising expectations for sanctioning of a state-owned Turkish bank by the U.S.

There are growing American concerns that Turkey is involved in a similar scheme to help Venezuela evade U.S. sanctions by importing gold. Lack of transparency in transactions raise suspicions that government officials in both countries benefit from the trade.  Erdoğan did not seem eager to allay the U.S. concerns when he met with Maduro's vice president Tareck El Aissami, who was sanctioned by the U.S. Treasury Department under the Foreign Narcotics Kingpin Designation Act when he visited Turkey in 2017 and 2018. The U.S. is monitoring the trade between Turkey and Venezuela and can take action against Turkey if the violation of the sanctions is assessed.

American efforts to isolate Iran and Venezuela are hindered by Turkey's trade relations with these countries. Even if the U.S. administration wishes to ignore violations of law by virtue of Turkey's geopolitical indispensability, it may not be able to prevent the Department of Treasury, Congress, and Federal Law Enforcement Agencies from taking action against Turkey.

Turkey's unwillingness to cooperate against terrorism, and organized crime further complicates the relationship. In April, the U.S. Department of the Treasury’s Office of Foreign Assets Control (OFAC) designated six members of the Rawi Network for playing a key role in ISIS money laundering. The designation also revealed how the network operated almost freely in Turkey. Turkey's reluctance to crack down on jihadist networks is a major concern for U.S. authorities. Suspicions over the Turkish government officials' profiting from the oil trade with ISIS earned significant media coverage in recent years. Opposition MPs in Turkey claimed that Erdoğan's son-in-law was involved in illegal oil trade with ISIS.

Instability on Turkey's southern border and the loss of institutional capacity of law enforcement as a result of the extensive purges after the coup attempt in 2016 led to rapid expansion in illicit trading and smuggling. Heroin seizures in Turkey significantly declined after 2013. The salient feature of the recent resurgence of  organized crime in Turkey is its government-sponsored character. Erdoğan publicly praised some former crime bosses and began to employ them as his political allies.

It is becoming impossible for the U.S. to consider Turkey as a reliant partner in the fight against global terrorism, organized crime, and drug trafficking. The U.S. decision to designate Iran's Revolutionary Guard Corps (IRGC) as a terrorist organization and its commitment to regime change in Venezuela will further increase the possibility of sanctioning Turkey.

If the U.S. imposes sanctions on Turkey, that could act as the last push throwing the ailing Turkish economy off the cliff. This would render any efforts to normalize relations and save the alliance fruitless. But the fact that Erdoğan is motivated by his quest for survival more than rational foreign policy calculations, his dependency on his corruption network for staying in power can only lead to the undesirable outcome of a permanent breakdown.