assassination as a tool of the state

Austin Bay has posted some thoughts regarding the apparent murder of Alexander Litvinenko, and what it means about Putin's Russia. Quoting a Time Magazine article:

Meanwhile, there is the light–uncomfortably glaring–that the case sheds on modern Russia. Vladimir Ryzhkov, one of the few independent liberals left in the Duma, says, “The point is not whether Putin is responsible for these concrete murders. The point is that he is responsible for having created a system that is ruled by fear and violence.” Ryzhkov claims that the armed forces, Interior Ministry, FSB and those who have retired from them to join private security services “are running this country, own its economy and use violence and murder as habitual management techniques.” A U.S. businessman in Moscow seconds the argument. “While you in the press are obsessed by Politkovskaya and Litvinenko, you’ve missed that half a dozen major oil executives and another half-dozen major bankers have been murdered in the last few months.”

It seems clear that Putin is either using or condoning assassination and murder as a tool of the state. Assad's Syria has apparently also taken up the practice of state sponsored assassination, as evidenced by the killings of Rafik Hariri and Pierre Gemayel. On the other hand, the U.S. and Israel have both engaged in the practice, assassinating al-Qaeda and Hamas leaders on occasion. In the case of Russia and Syria, I'm 100% opposed to the assassinations that have occurred. In the case of the U.S. and Israel, I think there's a moral case to be made that supports the use of assassination as a tool of the state. But I'm not certain. Here are the key differences that I see between the "good" and "bad" assassinations:

• Russian and Syrian targets have included politicians and journalists that have been critical of Russia and Syria. None of their targets have been involved in any kind of violent aggression. None have been implicated in any significant crimes--Litvenko may well have been involved in some shady business (he came out of Russia's intelligence services, after all), but Russia hasn't made any allegations of criminal activity on his part.
  
• U.S. and Israeli targets have been leaders in organizations that are engaged in violent aggression against the U.S. and Israel. These targets have been personally implicated in violent criminal activity and would be subject to legal action if only the state could get its hands on them. These targets have been seeking refuge among populations that are not willing to cooperate in bringing them to justice.

In other words, the U.S. and Israel have been using assassination as a tool when it is the only realistic mechanism for bringing a violent opponent to justice. Russia and Syria have been using assassination as a tool when it is a convenient method for silencing an inconvenient critic or political opponent. I don't think I'm splitting hairs to suggest that U.S. and Israeli assassination policies seem to be legitimate cases of a state exercising its God-given authority to use force to punish evil:

Let every person be subject to the governing authorities. For there is no authority except from God, and those that exist have been instituted by God. Therefore whoever resists the authorities resists what God has appointed, and those who resist will incur judgment. For rulers are not a terror to good conduct, but to bad. Would you have no fear of the one who is in authority? Then do what is good, and you will receive his approval, for he is God's servant for your good. But if you do wrong, be afraid, for he does not bear the sword in vain. For he is the servant of God, an avenger who carries out God's wrath on the wrongdoer.

Romans 13:1-4

Or am I missing something?