Syria is not an easy call for President Obama. With so many lives potentially at stake, caution always deserves a home at the heart of American foreign policy. Still, there's a difference between caution and inaction.

Even if he won't intervene directly in Syria, President Obama could and should take five other actions to constrain Hassan Nasrallah and Hezbollah, who are getting increasingly involved in Syria's civil war.

1. Arm select Syrian rebels

America should arm nationalist-minded Syrian rebels while mitigating the risks of groups like Jabhat al-Nusra accessing these weapons. With Hezbollah overtly engaged in Syria, the Syrian rebels desperately need an effective counter-balance. We should provide it.

2. Tighten sanctions against Hezbollah

Fortunately, the U.S. Treasury has already begun to take action in this area. But there's more we can do. Treasury should target the assets of Hezbollah politicians in Lebanon. We should pressure our allies to restrict Hezbollah's freedom of movement. In a similar vein, we should blacklist foreign companies that conduct major business with Hezbollah's allies.

3. Pressure the EU to list Hezbollah as a terrorist organization

The EU still grants extraordinary latitude to Hezbollah. This leniency offers the group two significant bounties — access to highly lucrative revenue streams, and an air of cultured legitimacy. Obama should dispatch John Kerry and the full power of American influence to encourage the EU to get tough.

4. Launch an aggressive PR campaign

Hezbollah has claimed many banners in its life — as an insurgency against the Israeli occupation of southern Lebanon, as a movement for Shia emancipation, and as a cross-sectarian resistance force. But in Syria, we're seeing the true face of Hezbollah — as an organization of brutal authoritarianism that holds a shallow tolerance for any interest except raw power. Obama must bring attention to this rhetoric-reality gap. We must be very vocal and clear to exploit the growing criticism of Hezbollah in Lebanon, while also degrading the mythology from which the group wins much of its support.

5. Issue a presidential finding to authorize covert action against Hezbollah

A finding would allow the CIA to employ major covert action against Hezbollah interests around the world. Hezbollah is opposing key American interests. We shouldn't be sitting on the sidelines. Whether disrupting Hezbollah supplies to Assad, or sabotaging the group's financial holdings, or increasing U.S. support for Hezbollah's political adversaries, the U.S. could meet Hezbollah's aggression with a balanced yet powerful response. Our overall focus should be clear — to pull the rug out from under Hezbollah's feet.

The alternative is to be a bystander to the Syrian slaughter.