On March 19th U.S. Senators John McCain (R-AZ) and Lindsey Graham (R-SC) released a statement calling for military action against Syria.  The statement was this:
“We are extremely disturbed by reports that chemical weapons have been used today in Syria. President Obama has said that the use of weapons of mass destruction by Bashar Assad is a ‘red line’ for him that ‘will have consequences.’ If today’s reports are substantiated, the President’s red line has been crossed, and we would urge him to take immediate action to impose the consequences he has promised. That should include the provision of arms to vetted Syrian opposition groups, targeted strikes against Assad’s aircraft and SCUD missile batteries on the ground, and the establishment of safe zones inside Syria to protect civilians and opposition groups. If today’s reports are substantiated, the tragic irony will be that these are the exact same actions that could have prevented the use of weapons of mass destruction in Syria.”
Such decisions can be tough to make. Questions always arise as to whether U.S. intervention will be, on balance, helpful in the cause of stabilization. With regard to Syria in particular there are concerns about the composition of the rebellion, and whether those who will ultimately replace the Assad government will be friendly to U.S. interests. Additionally, there is the U.S. domestic situation to consider, specifically, a national debt that we are told is reaching crisis levels, and should not be, therefore, in sufficient health to withstand yet another foreign military adventure.
But those who take Catholic social teaching seriously can avail themselves of guidance to help them in their discernment in such situations by means of the Just War Doctrine. Since it is anticipated that many of our readers will be of that ilk, it will be useful to lay out the elements of the doctrine, and try to apply them to the Syrian situation.
The requirements of the Just War Doctrine are strict, and each requirement must be satisfied in order to give moral legitimacy to any military action. One such requirement is that “the damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain….” 
To comply with this requirement it would be necessary that either the United States was being attacked by Syria, or that Syria was launching a serious attack on the community of nations. But neither of those things are taking place. In fact, no nation is being attacked at all. The conflict in question is a civil war. The Just War Doctrine, therefore, does not provide justification for the United States to launch a military attack against Syria.
This should not prevent the United States from providing humanitarian assistance. There is no evil in doing such things as providing medicine to those who need it, or giving aid to refugees. But the Just War Doctrine reminds us that our eagerness for good works ought not to wander into military adventurism, the only inevitable outcome from which will be human suffering.