American legal justification for the attack on Syria

"“The Syrian regime has shown that it cannot and will not confront these safe havens effectively itself,” the letter states. “Accordingly, the United States has initiated necessary and proportionate military actions in Syria in order to eliminate the ongoing ISIL threat to Iraq, including by protecting Iraqi citizens from further attacks and by enabling Iraqi forces to regain control of Iraq’s borders."  So a Chinese diplomat living in LA can claim that the US government has not dealt with the gangs in LA effectively, and can then use that as a justification for bombing sites of LA gangs?