WASHINGTON (AP) — Before the U.S. attack on a Syrian air base, President Donald Trump accused his predecessor of doing nothing when Syria's government used chemical weapons against its population in 2013. Trump is right that President Barack Obama issued what amounted to an empty threat of military action. In a White House statement after what the Trump administration said was a bombing involving the nerve agent sarin in a rebel-held part of northern Syria: 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 that he would establish a 'red line' against the use of chemical weapons, and then did nothing. When evidence emerged in August 2013 of a large-scale chemical attack in the Damascus suburbs, more than 10 times deadlier than this past week's, Obama quickly signaled his intention to use military force. Derek Chollet, Obama's assistant defense secretary for international security affairs, wrote in Politico last year that he was initially shocked when Obama decided to go to Congress, because "it was clear the president had all the domestic legal authority and international justification he needed to act." [...] Obama turned to diplomacy when Russia offered him a way out. SEN.