The US president says the Syrian regime had "crossed many lines" with its latest attack on the rebel-held town of Khan Shaykhun in Idlib province.
US President Donald Trump on Wednesday condemned the suspected chemical attack in Syria, describing it as an "affront to humanity."
At a news conference with Jordan's King Abdullah II in the White House, Trump said the Syrian regime had "crossed many lines" with its latest attack on the rebel-held town of Khan Shaykhun in Idlib province.
He said he had changed his view of the Russian-backed Syrian regime leader.
"When you kill innocent children, innocent babies, little babies ... that crosses many, many lines, beyond a red line, many, many lines," Trump warned.
Trump did not go into detail about his new policy towards Syria, just told reporters, "You'll see."
TRT World's Tetiana Anderson reports from Washington.
King Abdullah II praised Trump's commitment to addressing the Israeli-Palestinian conflict and said he had hope for the Arab League peace initiative proposed for the region.
"The president's early engagement in bringing the Palestinians and Israelis together has been a very encouraging sign for all of us," he said at the news conference.
King Abdullah's visit came just one week after he hosted the 28th Arab League summit in which Arab leaders reaffirmed their commitment to the creation of a Palestinian state under a two-state solution.
Speaking at a joint press conference with Israeli Prime Minister Benjamin Netanyahu in February, Trump said he would be open to a one-state solution, upending a position taken by successive administrations and the international community.
Fight against Daesh
During the meeting of both the leaders at the White House, the fight against Daesh was also on the agenda.
Later at the news conference, Trump said the US and its allies will destroy the group to "protect civilization."
"We will destroy ISIS [Daesh] and we will protect civilization. We have no choice," Trump said referring to Daesh by an alternative acronym.
Trump said the Jordanian King Abdullah has been a leader in the fight to defeat Daesh "once and for all."