At least 10 more Turkish tanks on Thursday crossed the border into Syria a day after pro-Ankara Syrian opposition fighters ousted jihadists from the town of Jarabulus in a lightning operation.
The tanks were set to join those which had crossed the frontier on Wednesday in the so-called Operation Euphrates Shield, which Turkey says aims at ridding the northern Syrian border area of both Islamic State (IS) extremists and Kurdish militia.
Turkish President Recep Tayyip Erdogan said on Wednesday that the offensive had expelled IS from the Syrian town of Jarabulus, and pro-Ankara rebels reported the jihadists had retreated south to the town of Al-Bab.
The new contingent of tanks roared across a dirt road west of the Turkish border town of Karkamis, throwing up a cloud of dust in their wake before crossing the border, an AFP photographer said.
They were then followed by around 10 armoured vehicles.
The operation, the most ambitious launched by Turkey during the five-and-a-half-year Syria conflict, has seen Turkish special forces deployed on the ground and jet fighters striking IS targets.
They are supporting a ground offensive by hundreds of Syrian rebels who on Wednesday marched into Jarabulus and a neighbouring village after meeting little resistance.
"Syrian opposition (fighters) settled in Jarabulus and have started to take control of the villages and towns," Prime Minister Binali Yildirim told Haberturk television in an interview.
It was not immediately clear if the deployment of the new tanks on Thursday was aimed at securing Jarabulus or helping the rebels move into new territory.
But a Turkish official said on Wednesday that Ankara would "continue operations until we are convinced that imminent threats against the country\’s national security have been neutralised."
The official emphasised that the Syrian rebels were leading the way with "Turkey\’s main role to facilitate (the) advances."
The well-connected columnist of the Hurriyet daily, Abdulkadir Selvi, said the aims of the operation included creating a security zone free of "terror groups" and limiting the advances of Kurdish militia.
He said 450 members of the Turkish military had been on the ground on the first day of the offensive but this number could rise to 15,000.
The Hurriyet daily, citing military sources, said 100 IS militants had been killed in the offensive. It is not possible to independently verify the toll.
State-run news agency Anadolu said one rebel fighter was killed but the Turkish armed forces sustained no losses.
Jarabulus, a small town on the west bank of the Euphrates a couple of kilometres (miles) south of the border, had been held by IS jihadists since the summer of 2013.
But Erdogan had also emphasised that the offensive was also aimed at People\’s Protection Units (YPG) Kurdish militia who have also been active in the area.
Turkey sees the YPG as a terror group bent on carving out an autonomous region in Syria.
Ankara\’s hostility to the YPG puts it at loggerheads with its NATO ally, the United States, which works with the group on the ground in the fight against IS.
But US Vice President Joe Biden, visiting Turkey on Wednesday, made clear that Washington has strictly told the YPG not to move west of the Euphrates after recent advances.
"They cannot, will not and under no circumstances (will) get American support if they do not keep that commitment. Period," said Biden.
With the operation fully coordinated with the United States, US A-10s and F-16s warplane also hit IS targets in Syria in support of the Turkish offensive, a US official said.
Ankara has in the past been accused of turning a blind eye to the rise of IS but hardened its line in the wake of a string of attacks — the latest a weekend bombing on a Kurdish wedding in the city of Gaziantep that left 54 people dead, many of them children.
The Jarabulus operation proceeded at lightning speed with the town captured from IS just 14 hours after it was launched.
The speed of the advance stood in stark contrast to the long, grinding battles it had taken for Kurdish forces to recapture towns from IS in northern Syria, such as Kobane and Manbij.
Turkish media said that the jihadists showed little resistance and published pictures showing that the rebel fighters even had time to take selfies along the way.
The apparent efficiency of the operation also marked a major boost for the Turkish army whose reputation had been badly tarnished by the failed July 15 coup against Erdogan staged by rogue elements in the armed forces.