Syria is not a significant oil producer, but any sign of conflict in the region tends to trigger concern about potential disruption to crude flows across the wider Middle East, home to some of the world's biggest producers.
Trunp was apparently angered after the chemical attack on the Syrian town of Douma, which killed 40.
This was the reaction of Russian officials regarding United States and also a number of its worldwide nations who threatened the use of military actions against the Syrian govt and also its primary friend, Russia. Asked if Putin bears responsibility, Trump has said that "if he does, it's going to be very tough, very tough".
Senior officials in the defense establishment warned Iran that Assad would pay the price if Tehran acted against Israel from Syrian territory. "He will, everybody will". He's often said he doesn't like to broadcast in advance what he would do, in terms of military strikes.
The Pentagon is likely planning a larger strike than what US warships launched on April 7, 2017, in response to the Assad regime's use of chemical weapons, said a former senior Defense official familiar with planning for that attack. Trump responded then by launching Navy cruise missiles at a Syrian airfield.
One woman who refused to be identified because of fear for her security described herself as "trembling" and said she stocked up on food and is considering not sending her kids to school.
Syrian opposition activists and rescuers said poison gas was used on the rebel-held town near the capital, an allegation strongly denied by the Assad government.
On Monday, U.N. Syria peace envoy Staffan de Mistura cited the air base strike along with other recent events in Syria in a briefing to the Security Council, cautioning against a "situation of uncontrollable escalation".More news: Woman gagged to death in Hyderabad, rape suspected
Both Iran and Russian Federation have a significant military presence in Syria.
Responding to Trump's tweet, The Intercept's Glenn Greenwald observed Wednesday that the president's threat provides a "nice, chilling reminder of how unsafe and volatile confrontation with Russian Federation can be" and demonstrates "why those who have been demanding Trump be more belligerent are risky idiots".
"Russia vows to shoot down any and all missiles fired at Syria", Trump wrote.
"Our relationship with Russian Federation is worse now than it has ever been, and that includes the Cold War", Trump said.
Did Russia respond to Trump's tweet?
Spokeswoman Maria Zakharova questioned whether the idea behind military action was to "use the smart missiles to sweep the traces of the provocation under the rug". Some stocked up on food and prepared underground shelters while others taunted the USA president to go through with his threats.
USA officials have been consulting with global allies on a possible joint military response to Syria's alleged poison gas attack.
This is in contrast to an incident one year ago in which the USA government had video and other evidence of certain aspects of an actual attack by Syrian aircraft, which involved the use of sarin gas.
"There can be no role now for investigations by the United Nations", Mrs May said.More news: Algerian military plane crashes with over 100 on board, reports say
Speaking in the British city of Birmingham on Wednesday, May said "all the indications" are that the Syrian regime was responsible for a chemical weapons attack in Douma, adding that the use of such weapons "cannot go unchallenged".
Will an inquiry take place?
By inviting the worldwide chemical weapons watchdog to send a fact-finding mission to Syria, the government claimed it proved it was innocent of the allegations of using chemical weapons.
Had Trump planned to pull advisers out of Syria?
Despite the threat of a military aggression by the United States against Syria, the main streets of Damascus are calm and thousands of civilians are doing their everyday chores. Less than two weeks ago, Trump said he wanted to bring USA troops home from Syria.
The U.S. and Russian militaries have sought to avoid conflict in Syria, notably previous year in the Euphrates River Valley where they supported rival sides in the campaign against Islamic State militants. Trump has largely avoided criticizing Russian President Vladimir Putin by name, though he singled him out in a tweet over the weekend for supporting Assad.
How did we get here?
As the initiative was voted down by the USA, the UK, France and Poland; Russia's United Nations envoy Vassily Nebenzia once again called for the West to "refrain from the plans which you might be harboring with regards to Syria". On Wednesday, Poznikhir alleged that the White Helmets - a Syrian civil defense group - had "staged chemical attacks for the cameras" and that Russian chemical weapons specialists and medical personnel had found no trace of chemical weapons in the affected area.More news: Latin America unfazed by Trump bypassing summit