Turkish troops, armoured vehicles and special forces have moved three miles (5km) inside the Kurdish-controlled Afrin area of northern Syria.
Overnight airstrikes were also launched against US-backed Kurdish forces in the area with Turkish politicians telling reporters they intended to clear the area of all those they consider terrorists in a swift operation.
The country’s prime minister told reporters in Istanbul on Sunday that the main aim of the military action, codenamed Operation Olive Branch, is to ensure the security of Turkey.
But the operation, which has been trailed for days, is likely to further heighten an already tense relationship between Turkey and America.
The Turkish forces will be trying to create what is described as a 18-mile (30km) ‘safe zone’ inside Afrin, the Turkish Prime Minister Binali Yildirim said. He added troops entered Afrin at 11.05am on Sunday.
He went onto say if the Americans provided logistical support to the Syrian Kurdish group known as the YPG, they too would be considered legitimate targets.
“Any kind of logistic support is our target,” he told reporters.
Turkey has become increasingly frustrated at the American support of the YPG.
Turkey considers the YPG to be a terrorist group linked to the outlawed Kurdistan Workers’ Party (PKK) that has waged a bloody insurgency within its borders.
But while the PKK is designated a terrorist organisation by America, the YPG is not.
Instead, America has been arming the YPG as part of the operation to clear Syria of Islamic State militants or Daesh.
It’s been a festering source of annoyance for the Turks who view the YPG and PKK to be different branches of the same organisation with similar objectives that is creating an independent Kurdistan across Turkey, Syria and Iraq.
When the YPG (under the auspices of the US-sanctioned Syrian Democratic Forces) reclaimed Raqqa last year, they publicly staged a victorious parade through the city’s stadium and unfurled a giant poster of the PKK leader Abdullah Ocalan, who is jailed in Turkey.
The Americans rushed to condemn this provocative display but the damage was done.
Then when the Americans recently announced plans to create a 30,000-strong border security force mainly made up of Kurdish fighters, Turkey ramped up the rhetoric and has now matched it with on-the-ground action.
A few days ago, the Turkish President Recep Tayyip Erdogan said he hoped the Americans would not side with the Kurds during the Afrin operation and that ‘despite it all’, he hoped to continue working with the US.
He added he hoped America would rather support Turkey in what he described as its legitimate attempts to combat terror.