ANKARA, Turkey (AP) — Turkey’s president says the U.S. missile strike on a Syrian air base is a “concrete step” but argues that it’s not enough.

Speaking at a rally in the southern province of Hatay, which borders Syria, President Recep Tayyip Erdogan says the U.S. has recently made positive initiatives in Syria and Turkey supports all efforts to ensure the safety of the Syrian people.

Referring to the U.S. strikes against Shayrat air base, Erdogan says, “I want to express from Hatay that we evaluate this concrete step against the Assad regime’s war crimes using chemical and conventional weapons as positive.”

“But I don’t see this as enough,” Erdogan says, and repeats Turkey’s calls for a “terror-free zone” to be established. “Let us declare a safe zone in northern Syria on the Turkish border, which can be 4000 or 5000 square kilometers, let us build homes there and settle our Syrian citizens,” he says.