If Clinton is going to have an uphill climb on the issue of terrorism, it will be because these attacks -and potential future attacks- are seen as a failure of the status quo to keep Americans safe, Mahaffee said.

Julian Zelizer, professor of history and public affairs at Princeton University, told Xinhua that for Clinton, who has a pretty hawkish record, the challenge will be to highlight this record, combined with her experience, without alienating younger liberals who want a different approach to ending this threat.

"To point to her long record in handing these issues, including the killing of Osama bin Laden, to show voters that she in fact could put together a tougher response to these threats," Zelizer added.

Darrell West, vice president and director of governance studies of the Brookings Institution, told Xinhua that each candidate has good credentials for the argument that each is making.

Clinton has tremendous foreign policy experience and knows all the world leaders, so she will claim that she can be effective in today's chaotic situation, West said.

Trump will argue that it takes courage to protect the United States and he is better suited on that front, he added.

"The election may come down to which of those arguments carries more weight," he said.

Right now, Clinton has an edge in voter perceptions about her foreign policy experience, but terrorist attacks within the US will alter the dynamic and give Trump "an opening to push his own credentials," West added.