Turkey plan for Syria incursion in the works for over two years: Source

‘Turkey’s ground incursion into northern Syria, which Ankara claims is mainly aimed at fighting Daesh, had been in the making for over two years, a Turkish official has said.
The so-called Operation Euphrates Shield began on Wednesday featuring Turkish warplanes and special ground forces to rid the border area of Daesh terrorists and Kurdish forces, according to Ankara.
On Friday, Turkey sent four more tanks across the border into the Syrian city of Jarabulus where the sound of explosions rang out.’
Read more: Turkey plan for Syria incursion in the works for over two years: Source