According to "The Intercept", an internal National Security Agency document provided by Edward Snowden shows that Israel took rather unusual steps in its long-term hostilities with Syria back in August 2008.
Brigadier General Suleiman, educated as an engineer, was a top military and security advisor and close friend to Bashar al-Assad. Suleiman played a unique role in Syria's inner circle; he was a member of Syria's research board which dealt with the development of chemical and biological weapons as well as nuclear research and was Syria's contact with North Korea. As such, he was in charge of security arrangements for the North Korean scientists who were involved in the construction of the Al Kibar nuclear facility which was destroyed by Israel in 2007. It is also believed that he was connected to the provision of arms from Iran to Hezbollah in Lebanon.
After the bombing of the nuclear facility, Suleiman began to plan for an alternative reactor. His new mission was complicated by the fact that on August 1, 2008, we now know that a team of Israeli commandos entered the waters off Tartus, Syria and shot and killed 49-year-old Syrian General, Muhammad Suleiman (or Sulayman), as he was holding a dinner party at his seaside chalet in the Rimal al-Zahabieh resort.
Here is a screen capture from Time magazine showing the story as it was covered by the mainstream media in August 2008:
According to the narrative at the time, Suleiman was shot in the head, neck and stomach/chest at close range and it was believed that the killers escaped by boat. As well, Syrian authorities kept news of the assassination from the public for five days with some diplomats assuming that he was eliminated by Assad because of an internal power struggle.
Here is an excerpt from a 2008 analysis by the Institute for National Security Studies (INSS), speculating about the reasons behind the assassination:
"The internal Syrian arena is the most intricate possibility. The fact that Suleiman was viewed as one of the people closest to Asad suggests a number of individuals, especially at the very top of the Syrian leadership, who might have benefited from the assassination, part of a power struggle at the highest levels of the regime. Since 2000, Bashar al-Asad’s firm entrenchment of his rule has been accompanied by the removal of various senior officials – deposing them from positions of power and replacing them with people from his inner circle. The most prominent examples of this were the 2004 retirement of Syrian defense minister Mustafa Talas and a year later, the dramatic escape of Vice President Abd-al-Khalim Khaddam to France. After Mughniyah's assassination, various reports were published regarding tensions between Asif Shawkat, the head of military intelligence, and Bashar al-Asad.
There seems to be another locus of tension, between Shawkat and Asad’s brother Maher, who heads the elite Republican Guards. In this scenario, the assassination of one of the president’s inner circle may have been intended as a message from opposition elements, either from within the regime itself or from outside. At the same time, it is clear that from the intra-Syrian perspective, the implication of Suleiman’s assassination for the regime is worrisome, as it raises the possibility that there are individuals not loyal to Asad within his inner circle. Oustings, “disappearances,” and banishments of senior Syrian officials in the coming months may turn out to be connected to Suleiman’s assassination and to internal power struggles.
Regarding military issues and special projects: given the lack of available information, it is hard to point to a specific motive or individual who might have wanted Suleiman dead. If involved in this sphere, Suleiman would undoubtedly have been privy to sensitive technological information as well as other state secrets. Neither one of those represents a good enough reason to have him eliminated by someone on the inside. Asad’s regime has ways of removing people from the nexus of power, and assassination is not one of the common ones – unless Suleiman was intending to exploit the knowledge he had in a way detrimental to Syria, e.g., through defecting to the West, like former Iranian officer General Ali Reza Asgari did in 2007. In this light, the assassination might have served the Syrian regime both as a means of revenge and as a potent message to the inner circle."
INSS does go on to postulate that Israel may have been behind the assassination, however, it states the following:
"Moreover, from the Israeli perspective, it is possible that the risk inherent in such an operation would far outweigh its possible benefit; after the reported September attack on the Syrian reactor and the Mughniyah assassination – both of which have been ascribed to Israel – an assassination of one of the Syrian president’s inner circle might prove to be the straw breaking the camel’s back, and would push the two states towards a dangerous escalation."
Now, let's look at the current information. Here is a screen capture of the partially redacted document which was posted on the NSA's Intellipedia, an internal version of Wikipedia:
Note that the document states that the assassination of Suleiman was the first known instance of Israel (Mossad) targeting a legitimate government official. The document is also listed as "SI" in the top right hand corner of the first page indicating that the information was gleaned from signals intelligence, likely from the Israeli military:
At the time of the assassination, an investigation revealed that Suleiman had $80 million in cash in a basement room in his home in the mountains between Damascus and the Lebanese border as shown on this secret cable released by Wikileaks:
Since Israel was not involved in armed combat with Syria at the time of the killing, international law states that they had no right to kill the General. To this point in time, Israel and the NSA have not commented on the release of this information.