Dear Chas:

This is a very interesting question.

I had an acquaintance who was retired, with 30 years service, from the CIA. At the time I was considering applying to the CIA. After talking with him about it I decided not to apply. The job really requires giving your soul, especially for a field agent. As a Christian, it would be very difficult to work for any spy agency.

The answer to your question really parallels on the same evaluations of killing in war. I think that the principles of the just war provisions must apply here, even though they not apply in a direct sense. The just war doctrine states:

Avoiding war

2307 The fifth commandment forbids the intentional destruction of human life. Because of the evils and injustices that accompany all war, the Church insistently urges everyone to prayer and to action so that the divine Goodness may free us from the ancient bondage of war.

2308 All citizens and all governments are obliged to work for the avoidance of war.

However, "as long as the danger of war persists and there is no international authority with the necessary competence and power, governments cannot be denied the right of lawful self-defense, once all peace efforts have failed."

2309 The strict conditions for legitimate defense by military force require rigorous consideration. The gravity of such a decision makes it subject to rigorous conditions of moral legitimacy. At one and the same time:

- the damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain;

- all other means of putting an end to it must have been shown to be impractical or ineffective;

- there must be serious prospects of success;

- the use of arms must not produce evils and disorders graver than the evil to be eliminated. The power of modern means of destruction weighs very heavily in evaluating this condition.

These are the traditional elements enumerated in what is called the "just war" doctrine.

The evaluation of these conditions for moral legitimacy belongs to the prudential judgment of those who have responsibility for the common good.

The U.S. Navy SEAL Chris Kyle was a sniper during times of war. Thus, his assignment and actions consitute a valid function in war, assuming his targets were combatants.

In terms of a spy assassinating a foreign dignitary it depends upon the situation. As mentioned in the just war doctrine we can take such action when the "damage inflicted by the aggressor on the nation or the community of nations [is] lasting, grave, and certain."

The "community of nations" clause would allow for the U.S. to intervene upon aggressor nations even if the aggressor nation has not attacked the U.S.

Thus, how do we define "aggressor nation" and who is a "combatant" in that aggressor nation?

The obvious answer is that an aggressor nation is one that has attacked and/or invades another nation. But, also in this definition, in my opinion, can be a nation that commits "war crime" type actions upon its own people, such as genocidal actions, or the use of weapons of mass destruction (gas, chemical, nuclear) upon its own people, or other actions against its own people that offend common principles:

2313b Actions deliberately contrary to the law of nations and to its universal principles are crimes, as are the orders that command such actions. Blind obedience does not suffice to excuse those who carry them out. Thus the extermination of a people, nation, or ethnic minority must be condemned as a mortal sin. One is morally bound to resist orders that command genocide.

If all peace and diplomatic efforts have failed, and the action taken has serious prospects of success, and the action does not produce greater evils, then the action may be permitted.

In some cases the assassination of a foreign dignitary may be permitted if that dignitary is a crucial leader in ordering the his military or para-military to commit actions that are "lasting, grave, and certain" "contrary to the law of nations and to its universal principles" and all other efforts for resolution have failed.

A spy who kills another spy, or a guard, or other combatants is permitted, depending on the situation, under the Church's teaching on self-defense, or under the teaching on war in which a combatant must be killed to facilitate a lawful mission.

Debates ensue about whether this or that war, or this or that action meets the "just war" doctrine. The primary person to initially evaluate that are the leaders of the nation who takes action against the aggressor. Those decisions may come under scrutiny, including by the Church, when the leader's evaluation appears to obviously violation the just war doctrine.

As for the troops who go to war, or do the spy work, unless they commit actions contrary to the just "rules of war" or of human rights, they are simply doing their job and are not personally culpable for their actions. 

This evaluation and interpretation is my own based upon my own understandings of the philosophy and principles of behind and stemming from the Church teaching on these matters. Others may have differing views and interpretations.

I hope this helps.

God Bless,
Bro. Ignatius Mary