The move comes just days after President Erdogan vowed to postpone a strike on the Kurdish militia YPG. Erdogan has complained that a plan to remove the YPG from the border with Turkey has taken too long.
Turkey moved masses of troops to its border with Syria on Sunday, near a town held by US-backed Kurdish forces.
The move came just days after Turkish President Recep Tayyip Erdogan announced that his military would not strike at the Kurdish YPG militia following the announcement of the US withdrawal from Syria.
Turkish media reported that the soldiers were moving near Manbij, where US forces fighting "Islamic State" (IS) terrorists have been based.
According to the DHA news agency, a convoy of troops entered Syria overnight, into territory held by the Free Syrian Army (FSA), which has been supported by both the US and Turkey.
Erdogan has repeatedly vowed to dislodge the Kurdish fighters, which Turkey views an extension of Kurdish insurgents inside its own borders.
Agreed exit plan from Manbij
In June, the two NATO allies had agreed to a plan that would see the YPG exit from Manbij, but Ankara has complained that the timeline for this has been delayed too long.
On Wednesday, US President Donald Trump shocked allies abroad and within his own administration by announcing a sudden removal of most of the US soldiers stationed in Syria. The move was welcomed by Russian President Vladmir Putin, who has backed the Syrian regime, but condemned by figures like US Defense Secretary Jim Mattis and Brett McGurk, the US envoy to the anti-IS coalition, both of whom have since tendered their resignations.
es/jm (AP, AFP, Reuters)