While many papers regard the move as running counter to Japan's pacifist constitution, others praise Tokyo for honouring what they view as its international responsibilities.
"The prime minister's head is on the block," warns Tokyo's Mainichi Daily News, noting that Prime Minister Junichiro Koizumi had said he would accept responsibility for the consequences of the decision.
Asahi Shimbun sees a number of "unresolved issues".
"How can the deployment of the Self-Defence Forces (SDF) to an Iraq that is in a state of war be justified with the ban on the use of force under Article 9 of the constitution?" the paper asks.
It says it will be hard for Japan to "avoid the criticism of 'being part of the US military's exercise of force'".
Mainichi Shimbun criticises Mr Koizumi for being too "inward-looking" at Tuesday's news conference.
It says he failed to put the decision in an international context, focusing instead on justifications from the country's constitution.
It also warns against viewing Japan's role in Iraq as "indispensable".
"It is not like the whole world is pitching in and only Japan would be remaining idle," it notes.
Tokyo Shimbun says the government has been in "agony" over the decision.
It also expresses concern about the "danger awaiting SDF troops deployed in Iraq".
Backing
Yomiuri Shimbun, however, is more upbeat, saying the "historic decision" will allow Japan to assume the "self-evident responsibility" of providing assistance to Iraq.
If Japan were to sit on the sidelines... it would not deserve its description as a country 'occupying an honoured place in international society', as is mentioned in the Preamble to the Constitution," the paper says.
Another article in the same paper stresses that the government's plan "places more importance on humanitarian aid for Iraqi nationals than on support for the US".
"The government apparently wanted to reduce the emphasis on SDF support for US forces which might make the dispatch a target for insurgents," the writer says, citing analysts.
Sankei Shimbun says the move will send out a positive signal regarding Japan's stance on terrorism.
The decision "has served not only as a message to Iraq, but also as a strong statement that Japan will not give in to any terrorism", the paper says.
