Turkish air strikes in northern Syria threatened the safety of US military personnel and the escalating situation jeopardised years of progress against ISIS militants, the Pentagon said on Wednesday. The public comments represent the strongest condemnation by the US of Nato ally <a href="https://www.thenationalnews.com/mena/syria/2022/11/20/turkey-launches-air-strikes-into-syria/" target="_blank">Turkey's air operations in recent days</a> against a Kurdish militia group in northern Syria. “Recent air strikes in Syria directly threatened the safety of US personnel who are working in Syria with local partners to defeat ISIS and maintain custody of more than 10,000 ISIS detainees,” Pentagon's spokesman Air Force Brig Gen Pat Ryder said in a statement. Brig Gen Ryder said the escalating situation threatened the progress made in the fight against ISIS militants in the region. He added that the US recognises Turkey's “legitimate security concerns”. “Immediate de-escalation is necessary in order to maintain focus on the defeat-ISIS mission and ensure the safety and security of personnel on the ground committed to the defeat-ISIS mission,” Brig Gen Ryder added. The US has about 900 soldiers in Syria, mainly in the north-east of the country, who work with the Syrian Democratic Forces (SDF), which is led by Kurdish fighters from the YPG, to fight against ISIS remnants. President Recep Tayyip Erdogan said on Wednesday that Turkey's <a href="https://www.thenationalnews.com/world/2022/11/15/istanbul-attack-turkey-announces-new-offensives-in-syria-and-iraq-against-kurdish-groups/" target="_blank">air operations were only the beginning</a> and it would <a href="https://www.thenationalnews.com/mena/syria/2022/11/22/erdogan-threatens-ground-offensive-in-northern-syria-after-air-strikes-kill-dozens/" target="_blank">launch a land operation</a> when convenient after an escalation in retaliatory strikes. Ankara <a href="https://www.thenationalnews.com/mena/syria/2022/11/17/turkeys-erdogan-hints-at-military-operation-in-northern-syria/" target="_blank">launched air operations</a> at the weekend <a href="https://www.thenationalnews.com/world/2022/11/14/uae-strongly-condemns-istanbul-explosion-that-killed-six/" target="_blank">in retaliation for an Istanbul bomb attack</a> a week earlier that killed six people, which it has blamed on the YPG. No group has claimed responsibility and the PKK and YPG have denied involvement. Turkey has previously launched military incursions in Syria against the Kurdish YPG militia, regarding it as a wing of the outlawed Kurdistan Workers Party (PKK), which Turkey, the US and the European Union have designated as a terrorist group. This is not the first time Turkey's operations in northern Syria have threatened US personnel. In 2019, American troops in the area came under artillery fire from Turkish positions as Turkey waged an offensive against US-allied Kurdish militia groups at the time.