Over the past week, the U.S.-led coalition carrying out airstrikes against Islamic State positions in Iraq and Syria has expanded to include several new members. This has enhanced its overall combat power and spread the burden more equitably. The British parliament voted Sept. 26 to join the group and has already commenced airstrikes over Iraq. Denmark and Belgium also decided to participate in direct combat operations. These new partners join two European peers, France and the Netherlands, as well as Australia. Notably, these six countries have chosen to restrict their combat roles to Iraq. This contrasts with the role of the United States’ five Arab partners — Jordan, Saudi Arabia, Bahrain, Qatar and the United Arab Emirates — which have been carrying out airstrikes with the United States in Syria since operations expanded there Sept. 23.

This odd division of labor does not operate in the interest of efficiency but is instead an artifact of the complicated and juxtaposed reality on the ground and in the political arena. The battleground against the Islamic State is ostensibly divided between the sovereign states of Iraq and Syria. In reality, however, it is a single space spread over what has become an imaginary border. The divided coalition reflects the members’ divergent political views on how to manage the respective situations of Iraq and Syria. Ultimately, the arrangement artificially separates what should be treated as a single battlefield and a single enemy. This weakens the coalition, confuses desired outcomes and often limits operations to what will appease all members.