"The president's long standing opposition to this so-called safe zone in Syria is predicated on the idea that while it sounds good, it's much more complicated in practice to implement it, it raises all sorts of questions," Earnest explained. "Trying to secure and patrol and in some cases be in the position of repelling attacks over such a large territorial area would not be consistent with our national security interests."
Earnest noted that establishing a safe zone in Syria could possibly require the deployment of "thousands of military personnel" to monitor the area, which would mean a commitment of US ground forces, which President Obama has staunchly opposed.
The White House spokesperson also said that a safe zone could partition Syria and warned that the term no-fly zone was "misleading" because it was unclear "how much safety and security that would bring anybody" since the situation on the ground is so unstable.
Russia and the United States reached an agreement on a ceasefire in Syria, which took effect on February 27 and does not apply to terrorist groups operating in the country.
Earnest said that the ceasefire has so far proved "more durable" than most US administration officials had expected, and said that it had reduced the violence and allowed for humanitarian organizations to finally reached besieged areas in Syria.