Turkish President Tayyip Erdogan will hold a press conference during the NATO summit at the Alliance’s headquarters in Brussels on June 14, 2021.

Yves Herman | Reuters

WASHINGTON – Turkish President Recep Tayyip Erdogan gave no indication on Monday that Ankara’s deal with Moscow over the S-400 missile system, which sparked unprecedented US sanctions against the NATO ally, would be reversed.

Erdogan’s remarks followed his first face-to-face bilateral meeting with President Joe Biden on the sidelines of the NATO leaders’ summit.

“It was a very fruitful and sincere meeting,” Erdogan told reporters at NATO headquarters, adding that the two allies would continue to negotiate on a number of issues.

Biden also said the meeting with Erdogan was productive, adding that it was confident that the US is “making real progress with Turkey”

Under the Countering America’s Adversaries Through Sanctions Act (CAATSA), any foreign government working with the Russian defense sector is in the crosshairs of US economic sanctions.

In December, the Trump administration imposed CAATSA sanctions on Turkey after the NATO ally bought a multi-billion dollar Russian missile system. The S-400, a Russian mobile surface-to-air missile system, is said to pose a threat to the NATO alliance, as is the F-35, America’s most expensive weapons platform.

The move further fueled tensions between Washington and Ankara in the weeks leading up to Biden’s rise to the White House.

National Security Advisor Jake Sullivan told reporters on Sunday that Biden and Erdogan would discuss “problems in our bilateral relations” without explicitly naming the US sanctions.

Sullivan also said the two are expected to deliberate on a range of regional security issues that stretch from Syria to Libya to the eastern Mediterranean. He added that Biden will also have the opportunity to consult with his Turkish counterpart on how to face China and Russia.

Turkish President Recep Tayyip Erdogan (L) and US President Joe Biden (R) will meet on June 14, 2021 at the NATO summit at the headquarters of the North Atlantic Treaty Organization (NATO) in Brussels.

Murat Cetinmuhurdar | Anadolu Agency | Getty Images

When asked about the CAATSA sanctions imposed on Turkey, Kirkland & Ellis’ lawyers described them as “calibrated” but also potentially difficult to lift.

“The sanctions that have been introduced are a little more targeted,” said Sanjay Mullick, a partner at Kirkland & Ellis who specializes in the company’s international trade and national security group.

“The focus here was on licensing, technology, and not so much on prohibiting any financial transaction. The bottom line is a bit more calibrated, although sanctioning a NATO ally certainly makes sense, ”he added.

“This is a move that is normally not seen in the relationship with such an allied partner, although in this case it may have been triggered by Turkey’s involvement in activities contrary to previous US foreign policy decisions, such as those against in 2017 Russia were hit. ” “Abigail Cotterill, Counsel for Kirkland & Ellis’ International Trade and National Security Practice Group, told CNBC.

When asked about the Biden government’s possible lifting of the sanctions, lawyers said that unilateral action by the president was unlikely given the complexity of the matter.

“Usually yes, the president can do and undo, or at least work with Congress to do and undo something. This is a slightly clearer situation where there may be less flexibility and less agility, which requires a combination of legal authority and, of course, political will, ”explained Mullick.

“We might expect at least some coordination between the executive and Congress to be required, even if it is not,” added Cotterill.

“This really fits into the larger context of US-Russia relations and in some ways the sanctions against Turkey, without quotation marks, were a derivative of the law that put in place a mechanism to sanction anyone who fills the void when he engages in certain activities involving certain sectors of Russian defense, “said Mullick.

“And so Turkey went in there consciously, unknowingly, I think consciously,” he added.

Make a deal with the Kremlin

Turkish President Recep Tayyip Erdogan (L) and Russia’s President Vladimir Putin in April.

Adem Altan | AFP | Getty Images

In 2017 Erdogan brokered a $ 2.5 billion contract with Russian President Vladimir Putin for the S-400 missile system. The S-400, the successor to the S-200 and S-300 missile systems, debuted in 2007.

Compared to US systems, the Russian-made S-400 is believed to be capable of fighting a wider range of targets at greater distances and against multiple threats at the same time.

Despite warnings from the United States and other NATO allies, Turkey accepted the first of four missile batteries in July 2019. A week later, the United States removed Turkey, a finance and manufacturing partner, from the F-35 program.

A Russian S-400 surface-to-air missile system.

Sergei Malgavko | TASS via Getty Images

Due to the removal of Turkey from the F-35 program, the US defense giant Lockheed Martin offered the jets originally intended for Ankara’s arsenal to other customers.

Reports surfaced in October that the Turkish military began testing the S-400 system. Both the defense and state ministries condemned the apparent missile test off the Turkish Black Sea coast.

“The United States has made it clear to the Turkish government at the highest level that the acquisition of Russian military systems such as the S-400 is unacceptable,” said then State Department spokeswoman Morgan Ortagus in an email statement.

“The United States has made clear our expectation that the S-400 system should not be put into service,” she added.

An F-35 fighter jet is seen as Turkey receives its first F-35 fighter jet with a ceremony on June 21, 2018 in Forth Worth, Texas, the United States. Two such aircraft, destined for Turkey, have yet to leave American soil.

Atilgan Özdil | Anadolu Agency | Getty Images

The US sanctions, coupled with Turkey’s forced withdrawal from a lucrative defense platform, sent a strong message to other foreign governments considering future arms deals with Russia.

“How the Biden administration is handling the S-400 sanctions will set an important and lasting precedent,” said Thomas Karako, director of the missile defense project at the Center for Strategic and International Studies.

“Our allies, partners, and adversaries have seen the slow, reluctant, and tepid CAATSA sanctions being imposed by the Trump administration. Aggravating this story with further weakness would send an unfortunate signal to a host of other partners, ”Karako told CNBC.