The coalition had forces within six miles of the strikes, he added, but none were put in harm's way by the strikes.
"Clashes between the People's Protection Units [YPG] and the Turkish army in Derbassiye continue", reported Jesper Söder, a Western volunteer with the Kurdish-led Syrian Democratic Forces (SDF).
Ankara has vowed to combat groups inside Syria that it links to the outlawed Kurdistan Workers' Party (PKK), which has waged an insurgency inside Turkey for over three decades.
"It was an unsafe way to conduct operations", Dorrian said.
The U.S.is especially concerned that Turkey gave little advance warning to the U.S. Combined Air Operations Center in Baghdad and described only a general area in which they would take place, Dorrian said.
Col. John Dorrian, a USA military spokesman, said the lead time failed to provide adequate notice to reposition American forces or warn Kurdish groups with whom the United States is partnering against the Islamic States. While U.S. forces were not as close to the Turkish target area in Iraq, U.S. officials expressed criticism of the fact that the strike was conducted without the consent of the Iraqi government.
The anonymous official, who did not provide any further detail about the explosives or explain how the security services came to identify their origin, also claimed that weapons supplied to the PKK/PYD by the US had also been found in PKK camps. "Less than an hour of notification is an inadequate amount of time to have our forces leave the ops box area that was identified ... which was a very large ops box", he said, referring to the area in which USA forces are operating.
Turkish airstrikes Tuesday also hit areas in northwestern Iraq and killed at least five Kurdish Peshmerga fighters, Dorrian said.
"The YPG forces targeted a tank belonging to the Turkish army that was trying to enter the territory of Rojava", he added.
Turkey also rejected US charges that less than an hour's notice was given of the airstrikes.
The United States expressed concern over the attack, saying Turkey didn't coordinate with the USA -led anti-terror coalition. Foreign Minister Mevlüt Çavuşoğlu said both the USA and Russian Federation had ample warning. "But I know that there has been a significant amount of diplomatic activity between the two sides since that occurred", he told reporters. "We respect Syria and Iraq's territorial integrity", but Turkey had "a legitimate right with these interventions" because of the threats to Turkey posed by the YPG and the PKK.
"Turkey acts transparently on all issues".
Turkish President Recep Erdogan said the United States and Russian Federation were informed of the attacks.