Many Muslims in the Middle East reacted with a mix of fear, caution, suspicion and scorn on Friday to President-elect Donald J. Trump’s appointments of aides with hostile views toward Islam.

From Iraq and Syria and Lebanon and elsewhere, a range of people already skeptical about Mr. Trump said their doubts were only reinforced by announcements that senior security positions in his administration would be filled with figures like Lt. Gen. Michael T. Flynn, known for his outspoken antipathy toward Muslims.

“Trump chose @GenFlynn as his National Security Advisor. We must not shy away from comparing his anti-Muslim rhetoric to that of the Nazis,” Joey Ayoub, a well known Lebanese blogger, said on Twitter. He echoed the trepidation about General Flynn’s now-famous Twitter post that “fear of Muslims is RATIONAL.”

Struggling to understand what Mr. Trump’s ascent means for them and their war-ravaged region, some, however, expressed hope that he will confront militant Islamist extremists far more aggressively than the Obama administration has done.

Yet others fear Mr. Trump’s views — and his reliance on anti-Islamists in his cabinet — will be exploited as a recruiting tool by Islamic State operatives and other violent militants.

Mr. Trump’s suspicions toward Muslims “reinforces and ratifies the jihadist worldview,” said Charlie Winter, a senior research fellow at the International Centre for the Study of Radicalisation and Political Violence at King’s College in London. “Jihadists are always looking for evidence of this conspiracy against Islam.”

He said General Flynn’s elevation in particular “is deeply, deeply worrying.”

In Iraq, where modern history has been profoundly shaped by the decisions of American presidents, officials and citizens alike are weighing Mr. Trump’s harsh words against his promise to defeat terrorism.