While Mr. Trump’s Republican and Democratic predecessors often pursued significantly different domestic policies, on the whole their foreign policies did not radically diverge from administration to administration. And for good reason: America and its leaders, whatever their failings, have largely taken their international responsibilities seriously and found value and security in adhering to laws, legal obligations and political commitments that reassure allies, constrain enemies, advance stability and promote democracy and human rights. If he shrugs off previous commitments without clear cause, Mr. Trump may find that world leaders will start to wonder if his successors will treat his deals as indifferently as he is treating his predecessors’.
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Given the standard that Mr. Trump is setting for foreign policy reversals, his own decisions could eventually be overturned by his successor. But the damage to America’s standing as a trusted, reliable partner won’t be so easily repaired.