"Where is this going?" is one of many questions thrown up by US political leaders after President Trump's decision to have Iran's top military figure, Qasem Soleimani, killed.
The reaction to the news was swift - from Democratic presidential contenders, his supporters in Congress and from commentators.
Fears of escalation
Concern about where this is all leading was summed up by Democratic White House hopeful Pete Buttigieg on the campaign trail in New Hampshire.
"Taking out a bad guy is not a good idea unless you are ready for what comes next," he told voters.
"Mayor Pete" reminded his audience of his service in Afghanistan as an intelligence officer - and the questions he asked before taking any military action.
"Was this decision made carelessly, or was it made strategically? Was there any preparation for the secondary effects and the effects that are going to come after that from an extremely provocative act that both of the last administrations decided not to do in one of the most volatile and unstable times in one of the most volatile and unstable places in the world?
Front-running Democrat in the presidential race Joe Biden is praying that Mr Trump "listens to his commanders".
For him, "the prospect of direct conflict with Iran is greater than it has ever been" because he "just tossed a stick of dynamite into a tinderbox".
"Iran will surely respond. We could be on the brink of a major conflict across the Middle East."
The fear of escalation is taken up, too, by another rival for the Democratic nomination, Bernie Sanders.
"Trump's dangerous escalation brings us closer to another disastrous war in the Middle East that could cost countless lives and trillions more dollars," he says.
Top Congressional Democrat Nancy Pelosi taps into Mr Trump's failure to consult Congress.
"The full Congress must be immediately briefed on this serious situation and on the next steps under consideration by the Administration, including the significant escalation of the deployment of additional troops to the region," she said.
Trump did the right thing
Support comes from the president's Republican backers in Congress, including the Senate majority leader, Mitch McConnell.
"No man alive was more directly responsible for the deaths of more American service members than Qasem Soleimani," he told the Senate as it began a new session.
"He personally oversaw the state terrorism that Iran used to kill our sons and our daughters. He posed an ongoing threat to American lives."
Acknowledging that the assassination "may prove controversial and divisive", he urged senators to "wait to review the facts and hear from the administration before passing judgement on this operation and its potential consequences".
A strong supporter of Mr Trump, Senator Lindsey Graham was succinct: "Wow - the price of killing and injuring Americans has just gone up drastically".
And Republican chairman of the Senate Armed Services Committee, James Inhofe, has this warning for enemies of America.
From al-Baghdadi to Soleimani, America’s adversaries should have no doubt that @realDonaldTrump means what he says. America does not and should not seek war, but it will respond in kind to those who threaten our citizens, soldiers and friends – as the President has long promised.— Jim Inhofe (@JimInhofe) January 3, 2020
But from Rand Paul, who has been critical of US military intervention in the Middle East in the past, comes this:
If we are to go to war w/ Iran the Constitution dictates that we declare war. A war without a Congressional declaration is a recipe for feckless intermittent eruptions of violence w/ no clear mission for our soldiers. Our young men and women in the armed services deserve better.— Senator Rand Paul (@RandPaul) January 3, 2020
Could this reshape 2020 election?
Alexander Burns, writing in the New York Times, thinks it might.
The attack "rippled instantly through the Democratic presidential primary on Friday, forcing national security issues to the fore of a race dominated so far by domestic policy and perhaps stirring debates among Democrats over matters of war and peace".
"The degree to which military matters come to dominate the primary, in the remaining month before the Iowa caucuses, will likely depend on events in the Middle East, and how severe and visible any ensuing clash with Iran turns out to be," he continues.
There have been "only glancing disagreements about the role of the United States abroad and the proper way to resolve American military engagements in the Middle East and Central Asia".
And talking of the election, both MSNBC, a news channel which tends to be critical of Mr Trump, and the Washington Post draw attention to a video he produced in 2011.
In it, Mr Trump suggested a "weak and ineffective" President Obama would attack Iran to boost his re-election chances.
In a piece which tries to find where exactly Mr Trump stands on Iran, the Washington Post suggests the comments he made then "will lead to plenty of theorizing about Trump's own motivations now that he's in a re-election year".
Quin Hillyer in the Washington Examiner laments the lack of Democratic Party support for the military strike.
"American elected leaders should strive to present a united front to the world. If they can't actively support the president, the opposition can certainly express concern and reserve the right to make harsher criticisms later without showing the sort of open, strident divisiveness that plays into enemy hands.
"They should probably wait for the smoke to clear before they noisily undermine the commander in chief".
And from an unlikely source...
US actor Rose McGowan tweeted an apology - addressed to Iran.
"The USA has disrespected your country, your flag, your people," she said. "52% of us humbly apologize. We want peace with your nation. We are being held hostage by a terrorist regime. We do not know how to escape. Please do not kill us."
And then she dealt with the backlash...
Ok, so I freaked out because we may have any impending war. Sometimes it’s okay to freak out on those in power. It’s our right. That is what so many Brave soldiers have fought for. That is democracy. I do not want any more American soldiers killed. That’s it.— rose mcgowan (@rosemcgowan) January 3, 2020