US Defence Secretary James Mattis confirmed the strikes but insisted it did not mean the US was stepping up their efforts in the Syrian civil war.
Reports claim American jets struck more than 20 Syrian tanks as they moved towards a border crossing point in southern Syria where Western forces were based.
US forces struck President Assad's military to deter aggressive nature towards Western troops
Countries that support and oppose the missile strikes in Syria
Mon, April 10, 2017
European countries have been broadly supportive so far as President Trump ordered missile strikes against a Syrian airfield from which a deadly chemical weapons attack was launched
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SYRIA OPPOSES: President Bashar al-Assad's office denounced the U.S. strike as 'reckless, irresponsible behavior.'
Speaking during a meeting with Sweden’s defence minister Peter Hultqvist, Mr Mattis said: “We’re not increasing our role in the Syrian civil war, but we will defend our troops, and that is a coalition element made up of more than just US troops, so we’ll defend ourselves.
“If people take aggressive steps against us, and that’s been going on, it’s policy of ours for a long time.”
Although the Western commanders instructed their troops to demonstrate a "show of force", the Syrian troops refused to “move out of the deconfliction zone”, a source told Fox News.
A second official told the broadcaster: “They were building a fighting position close to a US coalition base."
Yet Mozahem al-Saloum, spokesman for the FSA brigade, told the Telegraph it was the Iranians, not the Syrians, who aimed to increase aggression towards the West.
Mr al-Saloum said: "The Iranians are the ones promoting their movement towards al-Tanf, using the slogan 'Fighting The Grand Satan'. i.e. the US and the international coalition.”
The attacks are the first the Pentagon has launched against Assad's regime since they rained 57 Tomahawk missiles on the Shayrat air base near Homs.
Syrian fighter jet increasing aggression as it drops a payload
Donald Trump's tomahawk missiles were the last strikes the US launched against Syria
President Trump said the missiles were launched to condemn the deadly sarin gas attack, which claimed the lives of 87 people.
A US Pentagon official backed Mr Mattis and said the attack on forces did not reflect an escalation. He added: “There is no change in policy.”