President Obama used a commencement speech at Rutgers University on Sunday to lob implicit criticisms at the presumptive Republican nominee, inveighing against policies and attitudes that clearly reflect those of Donald Trump.

Obama, who also accepted an honorary doctorate from the university, urged those sporting freshly inked diplomas to avoid a “pull up the drawbridge” mentality. “The world is more interconnected than ever before,” Obama observed. “Building walls won’t change that.”