The Memory Hole

Statement from the White House, 5 April 2017:

"Today's chemical attack in Syria against innocent people, including women and children is reprehensible and cannot be ignored by the civilized world," Trump said in a statement released by the White House. "These heinous actions by the Bashar al-Assad regime are a consequence of the past administration's weakness and irresolution.”
....
"President Obama said in 2012 he would establish a 'red line' against the use of chemical weapons, and then did nothing,” Trump continued. “The United States stands with our allies across the globe to condemn this intolerable attack."

Statement from Organisation for the Prohibition of Chemical Weapons 4 January 2016:

Veolia, the US firm contracted by the OPCW to dispose of part of the Syrian chemical weapons stockpile, has completed disposal of 75 cylinders of hydrogen fluoride at its facility in Texas.

This completes destruction of all chemical weapons declared by the Syrian Arab Republic.  The need to devise a technical solution for treating a number of cylinders in a deteriorated and hazardous condition had delayed the disposal process.

Commenting on this development, the Director-General of the OPCW, Ambassador Ahmet Üzümcü, said: "This process closes an important chapter in the elimination of Syria's chemical weapon programme as we continue efforts to clarify Syria's declaration and address ongoing use of toxic chemicals as weapons in that country."

Obama did a lot more than draw a line in the sand he then erased.  And Google is your friend.