Over the past week, Turkish President Recep Tayyip Erdoğan has been ramping up threats to invade more areas of northern Syria, saying June 1 that he plans to "clean up [the Kurdish towns of] Tal Rifat and Manbij of terrorists," and establish a greater "security zone" in Syrian territory along Turkey's border. Much of this region is controlled by the Syrian Democratic Forces (SDF), which Turkey considers to be a "terrorist organization" because of its ties to the Kurdistan Workers' Party (PKK)—a Turkey-based Kurdish separatist organization. It's not clear if Erdoğan will go ahead with a new incursion now, but some wonder if Western states (such as the US, which has backed the SDF) may be willing to turn a blind eye to such an offensive if Turkey backs off its objections to Sweden and Finland joining NATO. Hundreds of thousands of civilians were forced to flee the last Turkish offensive in northeast Syria in late 2019, and a reported 44,000 to 60,000 people have still not been able to go back home.

From The New Humanitarian, June 3. 

Note: The 2019 Turkish invasion greatly reduced the Kurdish autonomous zone in northern Syria, with much territory formerly controlled by the SDF and its allies absorbed into Turkey's "security zone." The towns of Manbij, Tal Rifat as well as Kobani and Qamishli remain under precarious Kurdish control, in an uneasy alliance with Assad regime forces. Afrin is the principal town held by Turkey and its local allies, but Ankara has maintained open designs to expand the "security zone." Turkey has meanwhile launched an offensive against PKK-aligned forces in northern Iraq.