"The responsibility to protect these and all other diplomatic premises in Iraq sits with the Iraqi authorities,the spokesperson said in a written statement toThe Sydney Morning Herald andThe Age,adding that all staff at the Australian Embassy had been accounted for and were safe.

"We are keeping a close watch on developments as the situation unfolds and we remain in close contact with the US and other allies,and our other security partners,as well as the Iraqi government.

"We note that the justified US strikes were conducted in response to an attack on a military base in Iraq that caused American and Iraqi casualties. Coalition forces are in Iraq at the invitation of the Iraqi Government,and we fully respect Iraqi sovereignty."

The spokesperson declined to comment on whether action had been taken to bolster security at the Australian embassy in Baghdad for operational reasons.

US Defence Secretary Mark Esper had announcedthe administration was sending 750 troops to the region as"an appropriate and precautionary action taken in response to increased threat levels against US personnel and facilities,such as we witnessed in Baghdad today."

Republican Senator Lindsey Graham,a Trump ally and foreign policy adviser,had breakfast with the President and said in an interview that Trump was determined to"have no Benghazi on his watch,"a reference to the 2012 attack on US government facilities in Libya that killed the US ambassador and three other Americans.

Republicans harshly criticised the Obama administration and then-secretary of state Hillary Clinton for the response to the Benghazi attacks and Trump's wariness over any comparisons between the two events was publicly on display on Tuesday.

"The Anti-Bengahzi!"he tweeted about his administration's response to the situation in Baghdad.

Graham said Trump is not looking for a fight and hopes Iran will take steps that allow tensions to be ratcheted down soon.

"The goal is to de-escalate,but it takes two to do that,"Graham said,adding that Trump and his national security team are discussing"a lot of options"he would not detail.

In general,the US has options to confront Iran indirectly through military action against its proxy forces in Iraq,Syria and elsewhere,and to increase economic and political pressure on Tehran. It could also retaliate against Iraq,an ally of both Washington and Tehran,for not doing more to protect the embassy and the American contractor whose death on Friday at the hands of an Iranian-backed militia set off the current crisis. The US responded to the contractor's death by carrying out air strikes on Sunday against Kataib Hezbollah bases near the Iraqi-Syrian border,killing 25 and injuring more than 50.

"The President is determined not to let Americans be attacked without them paying a price,"Graham said of Iran.

The developments in Baghdad came on the eve of the new year,when Trump is seeking reelection on a platform that boasts of strong international leadership and a commitment that the US will not be a global policeman for age-old conflicts.

"They're fighting for 1000 years,they're fighting for centuries. I want to bring our soldiers back home,"Trump said in October,as he announced that US forces had killed Islamic State leader Abu Bakr al-Baghdadi."I had absolutely nothing to do with going into Iraq,and I was totally against it."

Trump has long viewed US involvement in the Middle East as a political loser that only leads to the loss of money and lives,according to an adviser who spoke on the condition of anonymity to describe the President's views.

"I can tell you 100 per cent that the President has no desire to get into some kind of new conflict in the Middle East during 2020,"this person said.

This northern fall,Trump withdrew all but a few US forces from Syria to make good on his promise to shake off the sand of faraway Middle East conflicts,but the move was condemned by both Republicans and Democrats because it allowed Turkey to move against the Kurds,who had been allies of the United States in the fight against the Islamic State. Trump sought to portray his decision as a win after a ceasefire was declared,but his detractors countered that only occurred because Turkey had already achieved what it wanted in the region at the expense of the Kurds.

Trump has distanced himself from the current Iraqi leadership and criticised its stewardship of oil resources. The White House issued only a cursory summary of a phone call on Tuesday between Trump and the country's placeholder prime minister.

"The two leaders discussed regional security issues and President Trump emphasised the need to protect United States personnel and facilities in Iraq,"the statement said.

"Regional security issues"is often shorthand for the White House view that Iran stirs up trouble throughout the Middle East and endangers Israel. Some of Trump's advisers view Iraq as a long-term US partner and a foothold of US-backed democracy in the Middle East,while others mainly see Iraq through the prism of its next-door neighbour Iran.

Trump has wanted to talk to Iran's president in an effort to strike some kind of deal,a move opposed by many in his administration,that he contends would be far better than the nuclear agreement the Obama administration struck with Tehran and that Trump abandoned soon after taking office. But there has been little progress on that front and the attack on the embassy appeared to make those talks even less likely in the near future.

Tensions were also high between Washington and Baghdad before the embassy assault,as officials traded accusations over Sunday's US airstrikes that Iraqi leaders called a violation of their country's sovereignty.

"I think the first thing he should be thinking about is stabilising the Iraqi government and not putting more pressure on it,"said Christopher Hill,a former US ambassador to Iraq."If the net result of all this is an unstable Iraqi political situation,we will be sucked into it one way or another."

Ryan Crocker,also a former US ambassador to Iraq,said Trump should think carefully about how his next steps will be viewed by Iran,which has its own calculations to make about how far to go in flexing its influence. Crocker welcomes Trump's stated interest in negotiating with Iran eventually,but said the president is raising the likelihood for conflict or miscalculation now.

"Trump sends a lot of different signals,"that Iran may not be able to interpret,he said."I just hope that they took that into account before those F-16 strikes that with that level of force,the chances of some kind of response are pretty high."

'It's a pressure cooker and it's going to blow.'

Former US army general Barry McCaffrey

Former Army general Barry McCaffrey,who has led troops in Iraq,said Trump is making it harder for Iran to back down.

"The economic sanctions on Iran are choking them,and they're looking for a way out. Our own demands have been maximalist - and in public,"he said."It's a pressure cooker and it's going to blow."

McCaffrey and Hill noted that Iran has more military resources in and around Iraq than the United States.

"Trump has dealt with this in the worst possible way. He's publicly,not privately,confronting the Iranians not on a conflict of our choosing but of their choosing,"McCaffrey said.

Iraqi security forces appeared to do little to prevent the initial assault on the embassy perimeter but later intervened,erecting a steel barrier at the smashed gate into the compound's reception area.

Some Iraqi protesters set up tents outside the compound on Tuesday night,condemning the air strikes and vowing to stay until all US troops and diplomats leave Iraq.

Douglas Ollivant,a former Army officer and National Security Council official who served in Iraq,questioned why Trump didn't retaliate for the contractor's death with a strike at Iranian assets in Syria rather than in Iraq. The US has no stake in the Syrian government the way it does in the Iraqi one,and both have interwoven ties with Iran,Ollivant said.

The militia attack that killed the US contractor"clearly gave the Iran hawks the justification they needed to strike Iranian-affiliated groups inside Iraq,"said Ollivant,now managing partner at the Iraq-focused consultancy Mantid International.

As for what Trump does now,Ollivant said the President may have less leeway than he imagines to reduce involvement in Iraq.

"We're now on our second president in a row that seems unable to disentangle themselves from this just by clearly wanting to,"he said.

The Washington Post