<p>President Trump issued a rare criticism of Russian President Vladimir Putin on Sunday after a banned chemical weapon was used on civilians in a rebel-held town near Damascus. ;</p>
<p>&ldquo;President Putin, Russia, and Iran are responsible for backing Animal Assad,&rdquo; tweeted Trump. &ldquo;Big price to pay. Open area immediately for medical help and verification. Another humanitarian disaster for no reason whatsoever. SICK!&rdquo;</p>
<p>Trump also criticized President Obama for failing to respond to a 2013 gas attack in Syria despite an earlier promise that such actions would cross a red line.</p>
<p>&ldquo;If President Obama had crossed his stated Red Line In The Sand, the Syrian disaster would have ended long ago! Animal Assad would have been history!&rdquo; tweeted Trump on Sunday. ;</p>
<p>Witnesses and rescuers said at least 42 people were killed in the attack Saturday, including ;entire families who suffocated inside their homes. At least 500 others required medical treatment. ;</p>
<p>Local doctors struggled to adequately care for the victims after a simultaneous attack on local medical infrastructure put the city&#8217;s largest hospital out of operation. ;</p>
<p>Images released by a Syrian paramedic group show dead children with foaming mouths, blue lips, and eyes wide open. Based on symptoms, doctors suspect the use of chlorine and nerve agents. ;</p>
<p>&ldquo;These reports, if confirmed, are horrifying and demand an immediate response by the international community,&rdquo; said State Department spokeswoman Heather Nauert. &ldquo;The Assad regime and its backers must be held accountable and any further attacks prevented.&rdquo;</p>
<p>The Assad government denies responsibility for the attack, which occurred ;almost exactly one year after Trump ordered a missile strike on a Syrian air base in response to a ;sarin-gas attack that killed nearly 100 people in the town of Khan Sheikhoun.</p>
<p>When asked about the potential for a similar response to Saturday&rsquo;s attack, White House adviser Thomas Bossert said, &ldquo;I wouldn&rsquo;t take anything off the table.&rdquo; ;</p>
<p>The Syrian coalition is urging the US, France, and Britain to retaliate, while relief groups are pushing for an independent investigation. Russia, which denies involvement in the attack, has warned of &ldquo;the most severe consequences&rdquo; if other powers seek to intervene militarily. ;</p>
<p>Washington&rsquo;s response to the attack will be a &ldquo;defining moment&rdquo; of Trump&rsquo;s presidency that comes as Assad sees America&rsquo;s &ldquo;determination to stay in Syria waning,&rdquo; says Senator Lindsey Graham (R-SC). &ldquo;If he doesn&rsquo;t follow through and live up to that tweet, he&rsquo;s going to look weak in the eyes of Russia and Iran. You need to follow through with that tweet. Show a resolve that Obama never did to get this right.&rdquo;</p>
<p>Trump last week suggested pulling US troops out of Syria, but has not issued formal orders. ;He plans to meet with advisers Monday as John Bolton begins his job as Trump&#8217;s new national security adviser. Bolton in the past has advocated for airstrikes on Syria. ;</p>