The Pentagon says this was a defensive strike, launched after pro-regime forces had violated an agreed deconfliction zone around a base at al-Tanf, near the Syria's southern border with Jordan and Iraq, where USA and British Special Forces are training rebels to fight ISIS.
NY [U.S.], May 19: The U.S.forces in Syria have bombed pro-Bashar al-Assad convoy at Tanf base that were advancing well inside an "established de-confliction zone".
US-led warplanes hit a pro-government convoy in Syria that ignored warning shots, weeks after president Donald Trump's administration launched Washington's first strikes against Damascus forces.
Russia's deputy foreign minister Gennady Gatilov said the destruction of the convoy was a "breach of Syrian sovereignty".
There were no immediate details on any civilian injuries.
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If I would have got into the back of her and run into her fuel cell or something like that, it could have been a lot worse than it was.
It wasn't clear to CBS News on Thursday why the vehicles had breached the zone, but Giglio reported that the USA strikes may have destroyed "regime and pro-regime militia vehicles". IS holds swathes of territory in northwestern Iraq and eastern Syria, but has lost considerable ground to US -backed military offensives over the past year.
"We are not increasing our role in the Syrian civil war, but we will defend our troops", Mr Mattis said.
Coalition forces, it went on to assert, had been operating near Al-Tanf "for many months, training and advising vetted partner forces" engaged in the fight against the Daesh terrorist group. Then, an unarmed Syrian bomber entered the zone but was intercepted by F-22 fighters. An exception was the US cruise missile strike that was launched last month in retaliation for Assad's chemical weapons attack that killed 86 people.
The US has been militarily involved in Syria since 2014, but has for the most part avoided engaging directly in the conflict.
USA -led troops helped repel a major IS attack on Tanf last month, while Russian warplanes bombed the base in June 2016.
Two US aircraft were dispatched as a "show of force" to get the Syrian vehicles to turn around, according to a US official. "Trump does not have Congressional authorization to attack Syria, a country that has not attacked U.S.".