The United States arming the PYD/YPG is a source of concern for Turkey as these terrorist organizations pose a threat to Turkey, President Recep Tayyip Erdoğan said Thursday.

"It is a source of concern," Erdoğan told Bloomberg in an interview, speaking about U.S. cooperation with those terrorist groups.

"Three days ago, America landed two planes loaded with weapons. Where? In Kobani. For whom? For the PYD and YPG," Erdoğan said, referring to a Syrian city within sight of Turkey's southern border.

"A very serious mistake is being committed before the world's eyes," he added.

Erdoğan said the U.S. mentality behind arming YPG forces is miscalculated. "You cannot use one terrorist organization to destroy another terrorist organization -- this is a big mistake. This is not good for Turkey because we are suffering at the hands of the terrorist organization that you seem to be defending." he said.

"Now, Al-Nusra is a terror organization. Al-Nusra in the same way is fighting Daesh. If those who fight Daesh are not terrorists then Al-Nusra too, is not terrorist."

Erdoğan said that PYD and YPG are affiliates of the PKK terrorist organization that is fighting Turkey. "They are together. They are the same," he said.

Erdoğan called once more for the international anti-Daesh coalition-made up of 65 countries-to "bring down Daesh" without the help of terrorist groups. "Don't worry about that. We can do that together," he said.

Erdoğan said that trying to distinguish between "good" and "bad" terrorist groups constitutes "wrongdoing against Turkey".

"Because right now we are worried by the organizations you defend. These pose a threat to our country," Erdogan said, adding that those who give weapons to the PYD/YPG terrorist groups are strengthening future threats to Turkey.

On a possible safe zone in northern Syria, Erdoğan said that world leaders such as U.S. President Barack Obama, German Chancellor Angela Merkel, French President Francois Hollande, and even Russian President Vladimir Putin had previously agreed to the proposal. "But once we say let's move forward on this, unfortunately this step was somehow not taken," he added.

Erdoğan said they want infrastructure and residences to be built in the proposed safe zone so Syrians need not leave their country to flee the war.