Israeli security officials are concerned that a Syrian pullback of forces in Lebanon to the Bekaa could spur Hezbollah to renew violence on the Israeli-Lebanese border, outgoing Israel Defense Forces chief Lt. Gen. Moshe Ya'alon said Tuesday.

The Syrians may want to "bring about an increase in the terror threat" on their way out of Lebanon, Ya'alon told reporters in Tel Aviv. He said Israel must keep careful watch "and see that our interests are not harmed."

U.S. President George W. Bush on Tuesday demanded Syria pull troops out of Lebanon before Lebanese parliamentary elections in May and give way to a democracy movement providing hope in the broader Middle East.

"The Lebanese people have the right to determine their future free from domination by a foreign power. The Lebanese people have the right to choose their own parliament this spring free of intimidation," Bush said.

The U.S. president used a wide-ranging speech at the National Defense University to lend support to what he called a trend toward democracy in the Middle East and away from authoritarian rule, which he called the "last gasp of a discredited past."

"Across the Middle East, a critical mass of events is taking that region in a hopeful new direction," he said.

Democratic progress had been frozen for decades, he added. "Yet at last, clearly and suddenly, the thaw has begun."

Bush paid particular attention to Lebanon, where a pro-Syrian government has fallen due to protests over the February 14 assassination of former Lebanese Prime Minister Rafik Hariri, and where Syria is under strong pressure to withdraw 14,000 troops as well as intelligence personnel.

Pro-Syrian rally draws hundreds of thousands of Lebanese Hundreds of thousands of flag-waving Lebanese flooded central Beirut on Tuesday for a pro-Syrian rally called by Hezbollah that dwarfed previous Lebanese protests demanding that Syrian troops quit Lebanon.

Hezbollah and Lebanese security sources said one million people attended the rally, which Hezbollah chief Sheikh Hassan Nasrallah called to thank Syria for its "sacrifices" in Lebanon and to oppose a UN resolution saying militias must disarm.

"I am here to express my opposition to resolution 1559 because it demands the disarming of the resistance. Hezbollah is not a militia. It deters Israeli aggression against Lebanon," 30-year-old demonstrator Mona Srour told Reuters.

The rally came only a day after at least 70,000 people - up to 200,000, according to some estimates - had demonstrated in downtown Beirut, demanding nothing less than complete withdrawal of all Syrian troops.

Also on Tuesday, Syrian troops began redeploying to eastern Lebanon on Tuesday in the first stage of a two-phased withdrawal from the country, a Lebanese security source said.

"The redeployment to the Bekaa Valley has started in line with the first phase," the source said. He did not say which positions were being vacated, but witnesses reported several troop movements in a mountainous ridge east of Beirut.

The move began after a joint Syrian-Lebanese military committee agreed on the details at a meeting in Damascus.

Syrian President Bashar Assad and his Lebanese counterpart Emile Lahoud agreed on Monday to shift Syrian troops to eastern Lebanon this month. A statement said the Syrian and Lebanese military would then decide how long the Syrians stayed.

Earlier in Damascus, a Syrian official source said Syria would pull its security and intelligence personnel out of Lebanon along with its troops.

The source gave no timetable for the second phase of the pullout, but said: "This doesn't mean it won't be soon."