The Danish government on Friday announced it was joining the coalition to strike at the Islamic State extremist group, sending seven F-16 fighter jets to take part in airstrikes against the group in Iraq.

Britain and Belgium are also debating their involvement in the coalition Friday, while the Netherlands has already announced it will take part. The European countries do not plan to deploy in Syria.

Danish Prime Minister Helle Thorning-Schmidt said her government would send four operational planes and three reserve jets along with 250 pilots and support staff. The deployment will last for 12 months.

She urged other countries to participate, too. "No one should be ducking in this case. Everyone should contribute," she said.

A vote in Parliament is planned and is considered a formality. However, no date was immediately set for the vote.

In Britain Friday, Prime Minister David Cameron made an impassioned plea for Britain to join the coalition. Cameron told a tense House of Commons that there was no more serious issue than asking the country to devote armed forces to conflict. He repeatedly stressed that no combat troops were planned, but he could barely get through his statement, as lawmakers peppered him with questions about the move.

"I believe it is our duty to take part," he said.  "This international operation is about protecting our people, too, and protecting the streets of Britain should not be a task that we are prepared to entirely subcontract to other air forces of other countries."

Lawmakers are expected to approve the motion, which is supported by all three main parties and comes only days after Iraq's prime minister requested help.

The motion does not address any action in Syria. Critics say that would be illegal because Syrian President Bashar Assad has not invited outsiders to help.

Foreign Secretary Philip Hammond refused to speculate Friday on how long the military campaign could last, but lawmakers envision a long-term action.

"We are going into this with our eyes open," Hammond told Sky News, adding that the Islamic State group is a threat to national security.

Denmark and Belgium are considering Friday whether to join the coalition.