As this is a should question, you will likely get differing perspectives.
Answer 1
No, there is no real justification.
I can understand the arguments to stay completely out of the conflict which are typically motivated by: (1) movements for anti-interventionism by the USA, (2) increasing debts and costs for the US government, (3) exacerbation of US war losses, and (4) alienation with other countries. I can also understand the arguments to have a full-on intervention which are typically motivated by: (1) protecting the Syrian people by ending the Syrian Civil War, (2) promoting democracy in a future government of Syria, (3) ejecting Islamic Terrorist Organizations like al-Qaeda and Hezbollah, which are currently in Iran, and (4) responding to chemical weapons abuse.
However, a bombing of Syria fulfills nor assures the fulfillment of any of these objectives from either side. It will have no tangible long-term benefit in helping to resolve the Syrian Civil War for any party. It will not help protect Syrian civilians. It will cause Anti-US antagonism and military casualties. It is the "solution" which only worsens the situation.
The US should take a page out of the Saudi and Iranian playbook and support militias currently operating in Syria. Of course, they support fundamentalist groups (al-Qaeda and Hezbollah, respectively), but the US could support thos militias that have a democratic outlook and provide skills, training, and weapons to them. This would minimize US costs while promoting democracy and the safety of Syrian citizens.
There are no US troops in Syria, so there is no-one to withdraw.
They claim that the ISIS terrorist group is located there.
No.
they throw bomb to other country
NO. That is not nice. Don't be anti-Muslim. They're not all mean. Garsh. Now, if they bomb us, then that's a wholenother story...
No. US civilian governance does not extend to any part of Syria or Iraq.
Let us say Syria has governates not states.
A man was throwing bombs in Boston and only one bomb came to Boston from Syria and don't blame it on Arabs blame it on the president in Syria he bashar alasaid .He doesn't want to give freedom to Syria and the bombs is from his army and the jagjh al-hur was trying to help Syria .so don't blame Arabs , blame bashar the Syrian president.
No the U.S shoud not get involved because the U.S. already have enough problems to deal with.
The hydrogen bomb.
It kiled millions of people.
"Bomb Bomb Bomb, Bomb Bomb, Iran." (John McCain - 2008)