President Bush has been warning for some time that terrorists hope to get their hands on nuclear or radioactive weapons. Now, there are reports the United States is deploying sophisticated sensors to deal with this possible threat.

Not long after the September 11 attacks on the World Trade Center and the Pentagon, President Bush warned that terrorists want to obtain weapons of mass destruction.

Sunday's Washington Post newspaper reports there are growing indications that al-Qaida terrorists are making progress toward that goal. The Post says that as a result, new sensors have been deployed at key positions: along U.S. borders, around Washington, and temporarily at last month's Olympics in Salt Lake City.

The report came as no surprise to Senator Richard Shelby of Alabama, the top Republican on the Senate Intelligence Committee. During an appearance on the ABC television program "This Week," Mr. Shelby said the threat is real.

"And I believe the administration is very much on the alert," he said. "We are doing everything we can to protect the security of the country against any possible nuclear weapons or a "dirty" bomb [a crude radioactive device]. But it is a real threat because of the proliferation not only of materials, but we don't know how many bombs are missing from the Russian inventory. I hope none, but the records are not good by any measurement."

In a separate interview, Senator John McCain said he too is worried about the fate of weapons from the old Soviet arsenal. The Arizona Republican told CNN's "Late Edition" those weapons could fall into the wrong hands.

"I think there has been a concern ever since the fall of the Soviet Union and the disintegration of the former Soviet Union when places like Kazakhstan and others were left with large amounts of materials as well as talent that were believed to be for sale," he said.

Idaho Republican Senator Larry Craig appearing on the same program said the Bush administration is right to take precautionary steps.

"We know that the Taleban and the terrorists were very interested in radioactive material and nuclear devices," he said. "Clearly the discoveries that we have made in Afghanistan and the raiding of these camps, the information that has been made available indicates that. Do we know that they have those devices? No we don't. Did we deploy radioactive detection equipment in Salt Lake? Yes, we did. And at other places like the Super Bowl? Yes, we have."

The Washington Post says the detection devices are only one part of a stepped up effort to protect Americans from terrorists who might be carrying crude nuclear or radioactive weapons. The Post says an all-out research and development program is under way to develop even better detection equipment. And it reports the Delta Force, an elite military commando unit, has been put on alert and ordered to kill or disable anyone caught with a suspected nuclear device.