Aaron David Miller is a senior fellow at the Carnegie Endowment for International Peace. He is the author of "The End of Greatness: Why America Can't Have (and Doesn't Want) Another Great President." He served as a Middle East negotiator in Democratic and Republican administrations. The opinions expressed in this commentary are those of the author; view more opinion articles on CNN.

(CNN) In the most recent Democratic debate, an animated Joe Biden exclaimed that ISIS "is going to come here" as a result of Trump's decision to abandon the Syrian Kurds and withdraw nearly all US troops from Syria.

After Trump's orders to withdraw, however, another wave of American troops entered Syria, leaving as many as 900 forces in the country. Still, the break in our alliance with the Kurds and the weakening in US counter-terror policy will undoubtedly allow gains for ISIS and other jihadi groups.

Is Biden right? Has Trump paved the way for ISIS to launch attacks on American soil? While the possibility can never be ruled out, the immediate threat ISIS poses to the US homeland is overstated. Far more concerning is the threat of homegrown terrorists, including right-wing extremists. The administration's willingness to alienate Muslims, and its failure to take the lead on sensible gun control legislation and minimize polarization only exacerbates these threats.

Given the chaos of the past several weeks, it's difficult to know precisely what the US policy is in Syria when it comes to fighting ISIS or partnering with the Kurds.

While Trump thanked the Kurds for their help when he announced the death of ISIS leader Abu Bakr al-Baghdadi, he failed to acknowledge the crucial role they played in helping the US. Not only have the Syrian Defense Forces provided foot soldiers in the battle against ISIS, the SDF commander-in-chief told NBC News they had an informant who offered critically important intelligence about the ISIS leader's whereabouts and details on his compound, which was then passed on to the US special forces. This alliance has now been eroded, and restoring trust will not be easy.