How far the covert assassination program has been an option for the governments?

The US government has been using assassination program against foreigners and Americans who can become a potential threat to their national interest and national security. COINTELPRO was developed by FBI and so many people were under the surveillance. The CIA's assassination of presidents and PMs around the world became quite popular strategy. They often use the local police officers, solders, local informants or mind controled individuals for the plots. The assassination of the Angolan president Lumumba might be a rare case for the CIA officer actually commiting the murder.

Of course, the CIA has executed covert assassinations of foreigners for decades. But tragically, Obama is expanding this program to include American, non-Islamic, stateside, homegrown terrorists.

It all started in January, when The Washington Post reported: "As part of the operations, Obama approved a Dec. 24 strike against a (Yemeni) compound where a U.S. citizen, Anwar al-Aulaqi, was thought to be meeting with other regional al-Qaeda leaders. Although he was not the focus of the strike and was not killed, he has since been added to a shortlist of U.S. citizens specifically targeted for killing or capture."

"A shortlist of U.S. citizens specifically targeted for killing"?

That's right. No arrest. No Miranda rights. No due process. No trial. Just a bullet.

While the Obama administration continues its Bush-blaming for the economy, it is mega-morphing Bush policy in covert ops overseas, which was, according to the Post, "to kill U.S. citizens abroad if strong evidence existed that an American was involved in organizing or carrying out terrorist actions against the United States or U.S. interests."
(http://www.humanevents.com/article.php?id=38266)

Japanese government often follows the policy of the US government. I think they might be applying the same strategy for tracking down the target on their lists. Or, the list might be extended by the allies to include the potential threats in the foreign countries. If a foreigner criticize the US government policy, the one would be listed as a threat.