US President Donald Trump's abilities as a dealmaker are being put to the test this week as he hosts Turkish President Recep Tayyip Erdogan, who brings along a list of grievances over American policies. And Trump's temporary national security adviser was a paid agent for the Turkish government, which must have been momentarily confidence-inspiring.
Given Giuliani's ties to the Turkish government, U.S. District Judge Berman has questioned whether his work with Zarrab would make the defendant less likely to pursue such options. The legislators specifically cited the Erdogan government's "increased direct threats against political opposition groups and minority communities including ethnic Kurds".
In 2013, US prosecutors say Erdogan pressured Turkish prosecutors to drop criminal charges in a high-level bribery case brought against Zarrab.
The YPG fights in a coalition of rebel groups that the USA considers its main ally in the Syrian conflict, but Turkish officials see the unit as a terrorist organization linked to an insurgency movement in the south of Turkey.
Russian Federation is the most powerful ally of Syrian President Bashar al-Assad's regime, and while much of the West supports Assad's removal, Russian Federation has insisted that he stay in charge.
US military officials have long argued in favor of supporting the Kurds in Syria against ISIS because they are such competent soldiers.
Tensions rose after Washington said it planned to arm Syrian Kurdish fighters belonging to the People's Protection Units (YPG), a group that Washington has backed in the fight against the so-called "Islamic State" (IS) but which Ankara considers a terrorist group.
Trump and Erdogan both emphasized the positive. However, President Putin made clear that Russian Federation would not follow Washington's example to arm YPG.
It seems unlikely that President Trump would change his mind on the issue after a face-to-face meeting, considering the decision to arm the Kurds was calculated over many months.
Erdogan and his military have been wary of Kurdish gains in Syria for several years, but Ankara became especially anxious last year after the YPG, with USA training and logistical help, captured significant territory from Islamic State. Fethullah Gulen, the self-exiled cleric who Ankara blames for a coup attempt against Mr Erdogan in July a year ago, is still living as a free man in the USA state of Pennsylvania, despite continued calls by Turkey for his arrest and extradition.
Trump has been keen to maintain a good relationship with Erdogan.
The PKK insurgency to secure Kurdish autonomy in Turkey has killed thousands of people. As Washington Director of Human Rights Watch, Sarah Margon, noted, "There's a credibility issue [for the U.S.] when it comes to the rule of law, particularly with the firing of Comey".
Mr Trump, after all, has had a history of going into meetings with adversaries only to leave as friends.
The controversial Turkish cleric is seen by his followers as an enlightened leader and by the ruling party in Turkey as a unsafe enemy and traitor.
But he said last week ahead of the trip that he views his visit to Washington as "a new beginning in Turkish-American relations".
Mr Erdogan has made clear he expects steps from Washington over the fate of Mr Gulen, who denies any role in the coup but whom Turkey wants to see extradited and face trial at home.
Zarrab's prosecution had been brought by Preet Bharara, the former USA attorney for the Southern District of NY, who was sacked in March along with other US attorneys named under President Barrack Obama. In his final days in office, President Obama had also chose to send heavier equipment to the YPG, indicating that the pro-Kurdish policy has broad support in the US.