In an interview aired on Turkish television station NTV, he said: "So where does the threat come from? It comes primarily from strategic partners", he stated, emphasizing that Washington continues to funnel truck- and planeloads of weapons into Northern Syria.
"We can not buy weapons from the United States with our money, but unfortunately, the USA and coalition forces give these weapons, this ammunition, to terrorist organisations for free".
In a statement, AK Party spokesperson Mahir Unal said: "Kilicdaroglu, whose will has been taken hostage, sent his 15 members to another party in an authoritative move, disregarding the choice of his voters in general elections on November 1, 2015".
The snap presidential and parliamentary elections called for June 24 last week caught Turkey off guard. The change takes effect after a presidential election is held.
Erdogan on on 21 April said Greece had become a "first stop" for coup suspects who later flee to other European countries. "We have evaluated it, and therefore we have reached [a conclusion]".
What's behind Erdogan's call for early elections?
"I will address 10,000 to 11,000 Turkish citizens in a closed gym in a country I will not announce at the moment", Erdogan said.
Turkey's top election authority has ruled that the fledgeling Iyi (Good) Party will be allowed to run in June snap elections, according to the state-run Anadolu news agency.
The party was formed in October after Iyi's founder and former interior minister, Meral Aksener, left the nationalist MHP party, following its decision to ally with the ruling Justice and Development Party (AKP).
"As a result of consultations with Mr Bahceli, we chose to hold elections on June 24, 2018, a Sunday", the president said, referring to MHP chairman Devlet Bahceli.
Under the changes, the number of lawmakers in parliament rises to 600 from 550, presidential and parliamentary elections are held every five years, and presidents can retain ties to their political party. The prime minister post is also abolished.
Kilicdaroglu said if Erdogan is victorious, the new system would establish Turkey as "the one-man regime".
He also said so far 83 members of the organisation have been brought back to Turkey.
FETO is a name Ankara gives for a movement led by Muslim preacher Fethullah Gulen who it blames for masterminding the failed coup aimed at unseating Erdogan.