UK lawmakers debate joining US in airstrikes to thwart Islamic militants in Iraq

A demonstrator bangs a drum at an anti-war demonstration near Downing Street in London, Thursday, Sept. 25, 2014. The British prime minister said late Wednesday he will ask Parliament to approve joining international airstrikes against the Islamic State group in Iraq. David Cameron announced the move in his address to the U.N. General Assembly. (AP Photo/Kirsty Wigglesworth) (The Associated Press)

A demonstrator bangs a drum at an anti-war demonstration near Downing Street in London, Thursday, Sept. 25, 2014. The British prime minister said late Wednesday he will ask Parliament to approve joining international airstrikes against the Islamic State group in Iraq. David Cameron announced the move in his address to the U.N. General Assembly. (AP Photo/Kirsty Wigglesworth) (The Associated Press)

A demonstrator holds a banner near Parliament in London, Friday, Sept. 26, 2014. Britain's Parliament is to debate and vote on the UK response to Iraqi's government's request for support against the Islamic State group. A result to the vote is expected late Friday. (AP Photo/Kirsty Wigglesworth) (The Associated Press)

British lawmakers have opened debate on whether to join the United States and a coalition of Western and Arab nations in airstrikes meant to thwart Islamic State group militants in Iraq.

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, that adding the Islamic State group is a threat to national security.