economic problems in Afrin.

I was aware that Turkey had begun constructing a wall some time ago-

The Russian-backed regime offensive from February 1-3 of this year opened a corridor to Nubl and al-Zahra, north of Aleppo city, and opposition forces in northern Aleppo around Azaz found themselves cornered with the regime to the south, ISIS to the east, Afrin to the west, and a closed Turkish border to the north.

The YPG and Jaysh al-Thuwwar, both members of the Syrian Democratic Forces (SDF), and began attacking the opposition to unite Afrin with the eastern Kurdish cantons. SDF is predominantly Kurdish YPG/YPJ forces—51,000 of its 55,000 are Kurdish—but it also contains 4,000 Arab and Syriac fighters. The fact that Jaysh al-Thuwwar has been prominent in attacking opposition forces around Azaz makesis Syrian territory. So, doesn't Azaz actually belong to Syria anyway. Clearly the Syrian government and army had intended to take Azaz.
And Turkey is cross border shelling to make it difficult for the Kurds to take the area..

Turkey is in a difficult situation. Although it has indicated that it is prepared to send ground forces into Syria, it is unlikely to do so without international backing. Instead, it has resorted to shelling Kurdish positions and supporting rebel forces against the YPG. On Friday, February 19, Turkish forces started shelling Kurdish villages and Afrin city. Turkish forces are attacking from Kilis (north of Afrin) and Sucuköy (west of Afrin). Turkish artillery shelled Afrin’s city center and its Ashrafia neighborhood, killing two civilians. The Turkish army also shelled the villages