Updated

The U.S. and Israel are closely monitoring Syria's suspected cache of weapons of mass destruction (WMD), fearing that terror groups could take advantage of the revolt against President Bashar al Assad to obtain blistering agents, nerve gas and long-range missiles, according to officials from both countries.

U.S. intelligence services believe Syria's non-conventional weapons programs include significant stockpiles of mustard gas, VX and Sarin gas and the missile and artillery systems to deliver them, The Wall Street Journal reported Saturday.

United Nations investigators also recently concluded that Damascus had been secretly constructing a nuclear reactor with North Korean help before Israeli jets destroyed the site in late 2007. U.S. and U.N. nonproliferation officials continue to worry that Pyongyang may have provided Syria with additional nuclear-related equipment.

"We are very concerned about the status of Syria's WMD, including chemical weapons," Israel's ambassador to the U.S., Michael Oren, said in an interview. "Together with the U.S. administration, we are watching this situation very carefully."

Israel has historically held concerns about the fall of the Assad regime, which has largely kept the Syria-Israel border quiet for the past 40 years. Still, Prime Minister Benjamin Netanyahu's government has increasingly voiced support for democratic change in Damascus.

"We see a lot of opportunity emerging from the end of the Assad regime," Oren said.

A senior US official said Syria's suspected chemical weapons arsenal "is of great importance and ... under intense study."

To read more on this story, see The Wall St. Journal article here.