Clinton has sought to make foreign policy a key part of the campaign as polls have consistently shown her more trusted on the subject than Trump. However, the role of foreign policy and national security in elections is hotly contested among political scientists and journalists.
Former Republican national security officials' endorsements of Clinton will harm Trump's foreign policy credibility.
However, the opposition of internationalist Republican hawks may boost Trump's 'anti-establishment' credentials.
In contrast, the Clinton administration can draw from a deep pool of Democratic foreign policy experts, a force for policy continuity.
Surveys show that US voters focus more on domestic issues, particularly the economy, terrorism and immigration.
