Will the US sanction Turkey over its purchase of the S-400 missile system? This question is causing disagreements among the highest officials in Washington.

A rare closed-door meeting occurred between 45 Senate Republicans and President Donald Trump on the changing relationship with Turkey and whether to impose sanctions. Sanctions against Turkey in response to the S-400 purchase are legally required by the Countering America’s Adversaries Through Sanctions Act (CAATSA), but can be waived by the president. This waiver is usually reserved for countries which are winding down their commitments with Russia, however, not for countries which are strengthening ties with Russia.

During this high-level, closed-door meeting, a “robust discussion” and “open dispute” occurred on this issue between Trump and Senator James Risch, head of the Senate Foreign Relations Committee. Risch supported strong sanctions against Turkey, but Trump indicated reluctance to sanction Turkey, saying that he preferred instead to negotiate. Turkish officials appear to be relying on Trump’s reluctance.

Bafflingly, US Secretary of State Mike Pompeo later warned Turkey not to “activate” its S-400 system, which has apparently confused top-level officials in Turkey.

This dispute occurs amidst mounting tension between Congress and the White House on how harsh to be on Turkey, as Turkey’s membership in NATO continues to be called into question and Turkey continues to threaten US allies — the Autonomous Administration of North and East Syria (AANES) and the Syrian Democratic Forces (SDF).

US Special Representative for Syria Engagement, Ambassador James Jeffrey, was visiting Ankara last week for negotiations on the Turkish proposal to create a militarized Turkey-Syria border. Jeffrey’s visit did not seem to bear any notable results, except for providing an opportunity for Turkey to draw an even harder line. During Jeffrey’s visit, Turkish foreign minister Mevlüt Çavuşoğlu threatened, “if the United States takes any negative action towards us, we will also take reciprocal steps.” This visit also occurred while the Turkish military posed new threats toward the people of North and East Syria by massing troops and equipment at the border. This military buildup could indicate a real desire to attack or could be just another diplomatic game.

The saber-rattling is indeed getting louder and louder from Turkey. Turkish officials spared no words in saying that they would indeed attack North and East Syria if a safe zone was not established according to their wishes, regardless of the diplomatic pressure from the US. President Erdoğan himself told an AKP gathering, “No matter what the result of talks with the US are over the establishment of a safe-zone along the Syrian border, we are determined to rip apart the terror corridor east of the Euphrates.”

Worryingly, several skirmishes have occurred at the border between Turkey and North and East Syria. So far these have not ignited large-scale conflict. In one incident, a rocket was fired over the border into Turkey, injuring five people, by an unknown person who was subsequently arrested by the SDF. Whether that person was working with Turkey, AANES, or another actor, or was acting alone, is not yet public information.

The US Mission of the Syrian Democratic Council attended events at the Hudson Institute and met with NGO personnel, met with Deputy Assistant Secretary Joel Rayburn at the US Department of State, and met with the offices of several senators and representatives in Congress.