The Chairman of the U.S. Senate Homeland Security Committee says extreme partisan anger on the left and right is increasing the risk of domestic terrorism in the United States. Senator Joseph Lieberman says there are already disturbing signs.
The anger is apparent at both ends of the political spectrum - from militias on the right, to anti-globalization demonstrators on the left. It has been mostly talk and little action, but Joseph Lieberman - a Connecticut independent - says there is plenty of reason for concern.
He points to the recent disclosure of an anti-government militia plot in the American Midwest. He says both politicians and commentators in the media need to cool their rhetoric.
"The level of discourse about our politics and about our country are so extreme and so incendiary that if you are dealing with people who may not be clicking on all cylinders and they have vulnerabilities personally, there is a danger that they are going to do what this group of militia - planned to do this week," said Lieberman.
During an appearance on the NBC television program Meet the Press, Lieberman said the threat of terrorism emanating from abroad is far greater. But he said the risk of a homegrown attack - like the Oklahoma City bombing of 1995 - is escalating.
"I would not overstate this threat," he said. "It is not as significant as the global threat of Islamist extremism, but it is real."
Michael Chertoff was the Secretary of Homeland Security during the final years of George W. Bush's presidency. He says modern computer technology has helped American extremists recruit new followers and develop tactics.
Chertoff also appeared on Meet the Press.
"The fact that people can get on the Internet, they can see the tactics being used in Iraq and Afghanistan creates a risk that those will be copycatted here," he explained.
The televised discussion on the terror threats facing the American people came just days after the suicide attacks on the Moscow subway that claimed dozens of lives.
Lieberman said law enforcement is taking additional steps to secure mass transit in the United States, but he said much more needs to be done.
"Non-aviation is the vulnerable part of our transportation system," Lieberman added. "And we frankly need to give it more than we are giving it now to protect the American people. I worry about this."
He points to other bloody incidents where terrorists targeted buses, trains and subways - including attacks on the Madrid transit system in 2004, London in 2005, and Mumbai in 2006.