US President Donald Trump's full statement on Syria missile attack

US President Donald Trump has addressed the United States' tomahawk missile attack on targets in Syria, saying the decision he made was of "vital national security interest".

The launch of 50 tomahawk missiles, which is the first US military action in the six-year-old Syrian Civil War, follows a deadly chemical attack on civilians on Tuesday (local time).

In a statement, Mr Trump explained why he ordered the launch on several key targets run by Syrian President Bashar al-Assad's forces.

"My fellow Americans, on Tuesday, Syrian dictator Bashar-al-Assad launched a horrible chemical weapons attack on innocent civilians using a deadly nerve agent. Assad choked out the lives of helpless 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.

"Tonight I ordered a targeted military strike on the airfield in Syria from where the chemical attack was launched. It is in the vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons.

"There can be no dispute that Syria used banned chemical weapons, violated its obligations under the Chemical Weapons Convention, and ignored the urging of the UN Security Council.

"Years of previous attempts at changing Assad's behaviour have all failed and failed very dramatically.

"As a result the refugee crisis continues to deepen and the region continues to destabilize, threatening the United States and its allies.

"Tonight I call on all civilised nations to join us in seeking to end the slaughter and bloodshed in Syria and also to end terrorism of all kinds and all types.

"We ask for God's wisdom as we face the challenge of our very troubled world. We pray for the lives of the wounded and the souls of those who have passed and we hope that as long as America stands for justice then peace and harmony will prevail.

"Good night and God bless America and the entire world. Thank you."

Mr Trump has previously been against military action in Syria, and was vocal in his opposition to former President Barack Obama's involvement there.