Turkish President Recep Tayyip Erdogan should be investigated and indicted for war crimes for his country’s military offensive in Syria, former prosecutor and U.N. investigator Carla Del Ponte said.

Del Ponte, a former member of the U.N. Commission of Inquiry on Syria, said in an interview published Saturday that Turkey had broken international law and had reignited the conflict in Syria.

“For Erdogan to be able to invade Syrian territory to destroy the Kurds is unbelievable,” said Del Ponte, a former Swiss attorney general who prosecuted war crimes in Rwanda and former Yugoslavia.

“An investigation should be opened into him and he should be charged with war crimes. He should not be allowed to get away with this scot-free,” she told the Swiss newspaper Schweiz am Wochenende in an interview.

Turkey halted its military offensive last week under a US-brokered ceasefire, Reuters reported.

Erdogan then negotiated an accord with Russian President Vladimir Putin whereby Syrian border guards and Russian military police began clearing the Kurdish YPG from within 19 miles of the Syrian-Turkish frontier.

Meanwhile, Erdogan vowed to send millions of refugees to Europe if its countries do not back his proposal to settle them in a Syrian “safe zone.”

Erdogan said he would “open the gates” for asylum-seekers if European countries failed to support his plans to resettle them in Syria’s northeast, the Independent reported.

“If Turkey’s plans for the return [of the refugees] … is not supported, we will have no choice but to open our borders,” he warned.

Also Saturday, Erdogan said Turkey will clear northeast Syria of Kurdish YPG militia if Russia does not fulfill its obligations under an accord that helped end the Turkish offensive in the region, Reuters reported.

Erdogan calls the YPG as a “terrorist organization” linked to Kurdish insurgents in southeast Turkey. Its Syrian offensive, launched after President Trump pulled out 1,000 US troops from the area, drew criticism from Turkey’s NATO allies.

“If this area is not cleared from terrorists at the end of the 150 hours, then we will handle the situation by ourselves and will do all the cleansing work,” Erdogan warned in a speech in Istanbul.

Turkey hosts about 3.6 million Syrians who fled conflict in their homeland, but wants to send up to 2 million back across the border.

Earlier this month, Erdogan told European leaders he would “send 3.6 million refugees your way” in retaliation for international criticism of his country’s military operation in northern Syria.