The deaths of two South Korean engineers in Iraq will not change the country's policy, the government says.
The deaths have a strong impact on public opinion
Seoul will still send more troops there, as planned, despite the killings near Tikrit on Sunday, the first losses South Korea had suffered there.
The foreign minister said it still wasn't clear if South Korea had been specifically targeted.
On Saturday, two Japanese diplomats and their Iraqi driver were shot dead, also near Tikrit, an anti-coalition centre.
President Roh Moo-hyun held a meeting of his National Security Council to discuss policy after Sunday's ambush, which left two more South Koreans seriously wounded.
All four men worked for a South Korean electrical company, contracted by the US military for reconstruction work.
In a weekend of violence, Spain lost seven intelligence agents and a Colombian contractor.
Meanwhile, US troops killed 46 insurgents who staged a series of ambushes on its forces in Samarra.
Young-Kwan said: "This case will not affect the issue of sending troops to Iraq. There has been no change in our policy on the troop dispatch."
He added that "the government will not give into violence".
South Korean officials have named the two men killed as
Kim Man-soo, 46, and Kwak Kyong-hae, 61.
One of the two injured men is in a critical condition.
"This incident is not terror against the military or a
public organisation but terror against civilians," said President Roh.
He has committed South Korea to sending a 3,000-strong contingent of troops to Iraq, building on the 675 South Korean medical and engineering troops already deployed since May in the south, around Nasiriya.
However, he has yet to decide whether to include combat troops in the deployment and correspondents say Sunday's killings could have major political ramifications.
Tokyo also suffered losses at the weekend, when two Japanese diplomats were shot along with their driver as they stopped to buy food at a roadside cafe.
They have been named as Masamori Inoue, 30, who worked at the embassy in Baghdad and Katsuhiko Oku, 45, who worked at Japan's London embassy.
Coffins pose difficult questions for the Japanese Government
They had been travelling to a conference on the reconstruction of northern Iraq in Tikrit.
Japanese Prime Minister Junichiro Koizumi said he was "furious" but his country would continue to meet its "responsibilities for humanitarian aid and reconstruction". Japan has pledged $5 billion in aid.
"Japan must not give in to terrorism," Mr Koizumi told reporters.
The attack raises new questions over Japan's troubled plans to send troops to Iraq.
Even before Saturday's attack public opinion was strongly opposed to any deployment of troops.
Japan's constitution bans its forces from operating in combat areas overseas and no Japanese military personnel have been killed in action since the Second World War.
An advanced fact-finding team is in southern Iraq to assess whether the conditions there are stable enough for the Japanese self-defence force to carry out its mainly humanitarian mission.
The government had hoped the first troops could be deployed within the next few weeks but the BBC's Tokyo correspondent says that this timetable may no longer be realistic.