Some Republican foreign policy veterans who came out against Donald Trump during the presidential campaign say they are sticking to their guns following his election victory, but a few others signalled that objections to serving in his new administration were softening.

Trump's stunning upset over Democrat Hillary Clinton has created a new dilemma for the Republican national security establishment, much of which had publicly distanced itself from their own party's candidate, declaring him unfit to lead. They must now decide whether to return to the fold.

Some career diplomats, intelligence officials and military officers are also facing a choice of whether to quit their posts because of concern that a Trump presidency would violate their principles, or else stay and try to influence policy from the inside.

However, State Department spokesperson Mark Toner said in Washington yesterday, "I wouldn't expect a mass exodus."

About 150 of the Republican party's most prominent national security specialists signed open letters in March and August in outright opposition to Trump's candidacy. One said he was "utterly" unqualified for the White House. The other warned that he would be "the most reckless president in American history."

While neither letter said the former officials would never work for Trump, their scathing critique was clearly intended to discourage fellow Republicans from supporting him. Trump responded at the time by deriding them as members of "the failed Washington elite" who "deserve the blame for making the world such a dangerous place."

A number of the signatories contacted by Reuters yesterday made clear that they were unswayed from their negative view of Trump and would not work for him.

However, they stopped short of urging others to also shun the next administration, which is widely seen as having limited foreign policy expertise at a time when the next president will face the challenges of Syria's civil war, the fight against Islamic State, a newly assertive Russia and the rise of China.

"I don't expect to be asked. I wouldn't serve. But there are others who will. It will be a matter of individual conscience," said Eliot Cohen, who served as counsellor to former secretary of state Condoleezza Rice and helped spearhead the March letter, which was posted on a blog called War on the Rocks and created a stir among Republicans.

"I'm concerned about his ignorance, the belligerence, the misunderstanding of how the world works," Cohen said of Trump, a wealthy real estate developer and former reality TV host who rode to victory on a wave of voter anger toward Washington insiders.

Max Boot, a foreign policy adviser to Republican Mitt Romney's 2012 presidential campaign and a supporter of the US-led Iraq invasion in 2003, said: "I won't have anything to do with Trump, but I don't know about others. I hope good people go into the government."

Waiting and watching

But others appeared to waver, with some saying decisions on whether to join the Trump administration could depend on how the president-elect behaves during the transition and who he appoints to senior posts.

Among the Trump allies said to be in consideration are former House of Representatives speaker Newt Gingrich and one-time United Nations ambassador John Bolton for secretary of state, and General Michael Flynn, a former head of the Defense Intelligence Agency, as national security adviser.

Dov Zakheim, a former Pentagon undersecretary who signed one of the dissent letters, said Trump would have to reach out beyond his circle of supporters to find enough qualified people to fill many important jobs.

"He will want to show that he is not dividing the Republican party, so he will extend an olive branch to those in the party who opposed him," Zakheim said. Asked whether he expected to be offered a post, he said: "I have no idea, as it's not up to me."

Bryan McGrath, a retired US Navy officer and co-organiser of the War on the Rocks letter, said he did not expect that those who signed it "were signing away employment rights, that they weren't going to work in a Trump administration".

If the president asks for your service, he said, "you have to take that request seriously."

Patrick Cronin, an Asia expert and former third-ranking official at USAID under President George W Bush, said that despite his earlier opposition to Trump, he eventually briefed his transition team and would continue to provide advice. But he said he was not interested in joining the administration.

Michael McFaul, President Barack Obama's former ambassador to Moscow and a Clinton supporter in the election, said the Republicans had a "deep bench of experience" for enlisting foreign policy experts.

Even as Trump prepares to form his foreign policy team, some career diplomats, intelligence officials and military officers are facing a post-election quandary.

Some said privately before Tuesday's vote that they would consider retiring or quitting, rather than working under Trump, who alarmed them during the campaign by questioning US-led alliances, praising Russian President Vladimir Putin, suggesting that Japan and South Korea should be allowed to have nuclear weapons and threatening to order the resumption of interrogation methods condemned as torture.

Other officials suggested they would wait to see how he acts once in office and who he names to senior posts, saying the responsibility for government service transcended any one president.

"If he keeps some of his campaign promises, about the use of torture, for example, many of us have discussed whether we are honour-bound to resign or to stay and try to have some influence from the inside. It's too early to say," one CIA officer said, speaking on condition of anonymity.

- Reuters