President Erdogan has claimed that the US in particular has provided a huge amount of military support to the Kurdish YPG in Syria.
Speaking to a congress of his ruling AK Party in the northwestern city of Bursa, he said allies had provided the YPG Syrian Kurdish military with 2,000 planeloads and 5,000 truckloads of weapons.
The Turkish leader said: “Now, apart from 5,000 trucks, there are weapons and ammunition from around 2,000 planes.”
Turkey believes the YPG to be closely linked to the Kurdistan Workers Party, who the government believe are terrorists.
The government used a failed army coup attempt in 2016 to justify a crackdown on pro-Kurdish political parties.
The US thinks the YPG in Syria are able to fight against ISIS.
Earlier this month, the Turkish President vowed to “drown” a US-backed border security force with Kurdish fighters in Syria.
Mr Erdogan said: “A country we call an ally is insisting on forming a terror army on our borders.
“What can that terror army target but Turkey?”
For many years during the war, the United States and Turkey worked together in bid to stop the Assad government.
However, a US decision to back Kurdish fighters in northern Syria in recent years has enraged Ankara.
President Erdogan has warned the US of what could happen by saying: “This is what we have to say to all our allies: don’t get in between us and terrorist organisations, or we will not be responsible for the unwanted consequences.”