By Bill Brubaker
Washington Post Staff Writer
Tuesday, March 14, 2006; 4:30 PM

Marine Corps Gen. Peter Pace, chairman of the Joints Chiefs of Staff, said today he has no evidence the Iranian government has been sending military equipment and personnel into neighboring Iraq.

On Monday, President Bush suggested Iran was involved in making roadside bombs, known as improvised explosive devices, that are being used in Iraq. And Defense Secretary Donald H. Rumsfeld last week accused Iran of sending members of its Revolutionary Guard to conduct operations in Iraq.

Today, Pace, the top U.S. military official, was asked at a Pentagon news conference if he has proof that Iran's government is sponsoring these activities.

"I do not, sir," Pace said.

The Bush administration's statements about alleged Iranian involvement in Iraq come amid increasing tensions between Washington and Tehran over Iran's nuclear program.

Rumsfeld, standing beside Pace, said today it is difficult to ascertain whether the Iranian government is directly involved in sending military equipment and personnel to Iraq.

"As to equipment, unless you physically see it coming in in a government-sponsored vehicle, or with government-sponsored troops, you can't know it" comes from Iran's government, Rumsfeld said. "All you know is that you find equipment -- weapons, explosives, whatever -- in a country that came from the neighboring country.

"With respect to people, it's very difficult to tie a thread precisely to the government of Iran. As we all know, there are pilgrimages where Shi'a come from Iran and around the world to go to holy places in Iraq, and they come by the thousands, sometimes tens of thousands. And so, that is also a difficult" to prove.

Rumsfeld again declined to offer a timetable for withdrawal of United States troops from Iraq. On a day when police around Baghdad discovered more than 80 bodies -- apparent victims of the sectarian violence that has gripped the country since the Feb. 22 bombing of a Shiite mosque in Samarra -- Rumsfeld called the day-to-day events in Iraq "clearly a very difficult situation."

Asked how long Americans might be fighting in Iraq, Rumsfeld said: "We know that insurgencies can last five, eight, 10, 12, 15 years and we've said that. We also know that insurgencies ultimately are defeated, not by foreign occupying forces but by the indigenous forces of that particular country. . . . "

Rumsfeld added: "Now, the implication to your question is, do we think we're going to be there four or five years more in terms of large numbers of U.S. ground forces? And the answer is no, I don't think so. Those are decisions for the president. They're decisions for the country."

Bush vowed yesterday to turn over most of Iraq to newly trained troops from that country by the end of this year.

But he made no commitments about withdrawing U.S. troops.

Rumsfeld said there are too many uncertainties to make such commitments. "Now if anyone in the world was smart enough to know precisely what the behavior of Iran, what the behavior of Syria, what the level of the insurgency would be; how fast they'll get a government; how confident the people will be in the new government, then one could probably draw a line and say, 'Gee, the trajectory of our troop reduction ought to be about like this,' " Rumsfeld said.