At a joint press conference with Jordan's King Abdullah on Wednesday, U.S. President Donald Trump stated that Syrian dictator Bashar Assad had "crossed a lot of lines with me. When you kill innocent children with chemical gas, that goes beyond red lines." For people who have been following the Syrian civil war since the beginning, his words were all too familiar: In the wake of the regime's chemical attack on the civilian population of Ghouta, a Damascus suburb, in August 2013, Trump's predecessor, Barack Obama, had made a similar statement – only to prove that he lacked the courage to follow through with his threats. Today, the only question that matters is whether President Trump will be remembered as a great leader who saved the Syrian people and restore America's role in the world, or a little man who followed in Obama's footsteps. Will the president of the United States, like Mr. Obama before him, talk tough but a carry a small stick? Or will he prove that he has the leadership skills and courage necessary to make history?To be clear, President Trump's strongly-worded statement on the Assad regime's atrocities was extremely important. For years, the enemies of the civilized world believed that the White House was more interested in PR stunts than policy. On Wednesday, something clearly changed. Furthermore, it was noteworthy that Trump showed the courage to acknowledge that he may have been mistaken about the situation in Syria and identify his ability to revisit his position on a number of issues as one of his strengths.Of course, the U.S. president will be attacked by the global media and charged with ignorance and stupidity. He will not receive the same kind of VIP treatment from reporters who could not wait to heap praise on Mr. Obama – who won a Nobel Peace Prize and proceeded to fail to enforce America's red lines and encourage the Assad regime, the Iranian-backed militants and others to commit further atrocities.It goes without saying that Washington suffers from a severe lack of credibility due to Obama's decision to appease Iran, stand against American allies in the Middle East and make concessions to China. Since 2013, oppressive regimes around the world no longer believe that the United States is an "indispensable nation" that will take a stand and make them pay if they kill innocent civilians with chemical gas.One appropriate saying is: "Fool me once, shame on you. Fool me twice, shame on me." Four years ago, America betrayed the world's trust by threatening airstrikes against the Bashar Assad regime but failing to take action. If President Trump fails to make Assad pay for his crimes against humanity, people will have no reason to think of Washington as a serious player in the international arena.Moving forward, the Trump administration should develop a comprehensive Middle East policy and resist the urge to buy in to the narrative created by Obama-era officials to work more closely with America's allies and friends in the Middle East – including Turkey, Israel and Saudi Arabia. From Raqqa to Damascus, from Manbij to Mosul, the only way to make a real difference is to have actual policy conversations with regional leaders and welcome their assistance in the military campaign against terrorism and dictatorship. The Turkish government, in turn, needs to stand by President Trump and help him to take necessary steps to fix Obama's mess.