Donald Trump has called on "all civilised nations to end the slaughter and bloodshed in Syria" after he ordered a military strike on the country.

The US leader said he the targeted airfield was the one from which a chemical attack was launched on Syrian civilians.

Speaking at his Mar a Lago resort in Florida, he added that it was in the vital national security interests of the US to prevent and deter the spread and use of chemical weapons.

There was "no dispute that Syria used banned chemical weapons," he said.

Mr Trump had said earlier that the deaths of more than 70 people in Khan Sheikhoun had changed his opinion of Syrian President Bashar al-Assad, whom US intelligence says is responsible for the attack.

"Using a deadly nerve agent, Assad choked out the lives of hopeless men, women, and children," he said. "It was a slow and brutal death for so many. Even beautiful babies were cruelly murdered in this very barbaric attack. No child of god should ever suffer such horror."

He added that "years of previous attempts at changing Assad's behaviour have all failed and failed very dramatically."

He continued: "As a result, the refugee crisis continues, and the region continues to destablise, threatening the US and its allies. Tonight I call on all civilised nations in seeking to end the slaughter and bloodshed in Syria and also to end terrorism of all kinds and all types."

Aleppo before the Syrian Civil War Show all 12 1 /12 Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man crosses a street in Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A vendor sits inside an antique shop in al-Jdeideh neighbourhood, in the Old City of Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, overlooking Aleppo city, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors walk inside Aleppo's Umayyad mosque, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk inside the Khan al-Shounah market, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man walks past shops in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk along an alley in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors tour Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A general view shows the Old City of Aleppo as seen from Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk near Aleppo's Bab al-Faraj Clock Tower, Syria October 6, 2010 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man stands inside Aleppo's historic citadel, overlooking Aleppo city, Syria December 11, 2009 Reuters

The Syrian government, and its Russian allies, have denied that the regime possesses chemical weapons stocks, which were handed over to the Organisation for the Prevention of Chemical Weapons (OPCW) after a deadly sarin gas incident in rebel-held Ghouta in 2013.

The strikes sent "an important message", according to Republican senators John McCain and Lindsey Graham, who have long pushed for stronger action against Syria, have issued a joint statement.