Foreign affairs intruded on the US presidential race with news of the death of the US ambassador in Libya. Until the brutal assault, the tightly contested race had focussed on the struggling US economy and unemployment.
"Make no mistake, we will work with the Libyan government to bring to justice the killers who attacked our people," said President Barack Obama at the state department.
Obama's response to the killings would be watched closely as they are threatening to turn into an election issue with Mitt Romney accusing his administration of backing the wrong side.
Even before the fullness of the overseas tragedy was known, Romney issued a statement that condemned the first response by the administration of President Barack Obama to the assaults.
On Tuesday, the US state department had sought to condemn the attacks - before the four deaths - by seeking to condemn equally the attack on Muslim religious sensibilities.
"I believe the administration was wrong to stand by a statement sympathising with those who had breached our embassy in Egypt," Romney said in a statement on Wednesday.
The White House has sought to distance itself from the state department statements, saying it was not cleared by Washington. Romney called that sending "mixed signals".
Commentators and analysts see in the attacks the potential of turning foreign policy into a central issue in the presidential election, which has so far been dominated by questions about the economy.
"The attacks in Libya and Egypt underscore that the world remains a dangerous place and that American leadership is still sorely needed," Romney said.
President Obama linked the attacks to 9/11, coming as they did on its 11th anniversary, saying "Today, we mourn the death of four more Americans."
"We will not waver in our commitment to see that justice is done for this terrible act," he said, adding, "And make no mistake, justice will be done."