The National Counterterrorism Center (NCTC) has blocked access to its web pages designating PYD as the "Syrian affiliate" of the terrorist PKK group.
Visitors to the site on Thursday were greeted with an error message when attempting to access the PKK section that gives profiles of the terrorist groups. By Friday, access was denied to the entire section.
Before it was blocked, the profile page for the PKK -- listed as a terrorist organization by the US -- mentioned the PYD as a cause for a "heightened threat to Turkey and increased tensions along the border."
The PYD "has increased its presence in northern Syria along the border with Turkey by establishing control in Kurdish areas," according to the web document.
That particular reference to the group was also included in the 2013 calendar edition issued online by the NCTC, although it has been removed for the current 2015 edition and the previous 2014 publication.
A separate NCTS Web page on Turkey's domestic terrorism doesn't list the PYD and an internet search for the agency's listed terror organizations sends users to a page that is unavailable.
The dynamics of the links between Turkey, the US and the PYD have caused a strain in the Ankara-Washington relations.
US officials have been adamant in recent weeks in their refusal to recognize the PYD -- or its armed wing, the YPG -- as a terrorist organization, instead calling the YPG a "reliable partner" in the fight against DAESH, supporting the group with weapons and training.
Ankara sees all three -- the PYD, YPG and the PKK -- as terrorist organizations, and has frequently pointed out the active link between these groups in Turkey and Syria.
Turkish Prime Minister Ahmet Davutoglu has dubbed the YPG "a pawn of the Syrian regime," citing a Feb. 17 Ankara terror attack that left 28 people dead and 81 injured.
Turkish officials have determined that the attack was carried out jointly by a Syrian-national YPG member and PKK terrorists based in Turkey. A day before the attack, Syria's envoy to the UN said the PYD enjoys the support of not only the US but also the Assad regime.
"These Syrian Kurds supported by the American administration are also supported by the Syrian government, just for your kind information," Bashar Ja'afari told reporters.
The Turkish military shelled PYD/YPG positions in northern Syria for a week beginning Feb. 13 in response to artillery fire from PYD forces based around Aleppo's Azaz town, located just 6 kilometers (4 miles) from the Turkish border.
The link to the NCTC's PKK (KGK) profile can be found at http://www.nctc.gov/site/groups/kgk.html.
The agency defines the PKK is a precursor to Kongra-Gel, or KGK, an umbrella organization that includes other domestic terror groups.