Israeli warplanes struck Hezbollah (search) guerrilla bases in southern Lebanon late Tuesday, threatening to re-ignite another Arab-Israeli front that has been mostly calm for years.

Israel said it was retaliating for a Hezbollah attack that killed one Israeli soldier and wounded another a day earlier, and said the attacks were intended as a message to Syria, the main power broker in Lebanon.

The United States blamed Hezbollah guerrillas for the escalation and cautioned Syria against giving support to the Lebanese militant group.

There was no word on casualties from the airstrikes in a valley six miles north of the Israeli border near the Mediterranean coast, Lebanese security officials said.

One target, a Hezbollah training position, took a direct missile hit and the sound of exploding ammunition was heard in the area, the officials said. They said they couldn't determine the extent of damage because of the remote location.

At least three air-to-surface missiles were fired in the two raids, the Lebanese officials said on condition of anonymity. Israeli military spokeswoman Maj. Sharon Feingold said the targeted positions were used by Hezbollah to launch attacks on Israel.

Meanwhile, Israeli troops tore down part of a synagogue at a West Bank (search) settlement outpost Tuesday but made no attempt to move adjacent trailer homes, prompting accusations the government isn't serious about meeting U.S. demands to dismantle dozens of the outlawed sites.

Demolition on a far greater scale took place in the Gaza Strip (search), where army bulldozers smashed 25 houses and flattened a mosque in a Palestinian refugee camp, leaving 400 people homeless, local officials said. The military said it targeted buildings from which shots were fired at Israeli forces.

Palestinian Prime Minister Ahmed Qureia (search) charged that the Gaza operation and the air strike in Lebanon were "clearly intended at exploding the entire area." He told The Associated Press, "This is very dangerous."

Hezbollah's TV station Al Manar quoted leadership sources as saying the attacks would not deter the group from "confronting any violation" by Israel of Lebanese territory. The Shiite Muslim guerrilla group has maintained offices and observation posts in southern Lebanon since Israeli troops ended an 18-year occupation of the area in 2000.

In past years, attacks and counterattacks have spiraled into wider conflicts involving Hezbollah rocket attacks on Israeli border towns and Israeli air and artillery strikes of southern Lebanon and infrastructure targets deep in the country.

There have been no serious flare-ups since the end of the Israeli occupation. While Israel is engaged in a bloody conflict with the Palestinians in the West Bank and Gaza Strip, its front with Syria on the Golan Heights has been quiet since the 1973 Middle East war.

In Washington, Secretary of State Colin Powell said it was unfortunate that Hezbollah had caused a need for Israel to respond.

"The deliberate action that they took, which resulted in the loss of life, once again demonstrates the nature of that organization," he said. "We believe that all parties interested in peace should condemn that kind of action by Hezbollah."

Powell said Syria should understand that any support for terror groups destabilizes the Middle East. The State Department calls Hezbollah a terrorist group. But in Lebanon and in many parts of the Arab world Hezbollah is considered a legitimate resistance movement.

Israeli officials said the missile strikes were retaliation for an incident Monday in which Hezbollah guerrillas fired an anti-tank missile at an Israeli military bulldozer that crossed into Lebanon.

Israeli commanders initially denied the bulldozer had crossed the border, but the Israeli army commander in the area, Col. Yair Golan, told Israel Radio on Tuesday that part of the vehicle had crossed into Lebanon while digging up explosives.

Security officials said it went about 20 yards into Lebanon.

Israeli officials blamed Syrian President Bashar Assad for the attack.

"If President Assad thinks he's going to use Hezbollah as the long arm in the fight against us, he should know that our response will be very clear," Israeli Foreign Minister Silvan Shalom said.

Israeli military officials said commanders decided to attack Hezbollah instead of Syria in order not to inflame the situation. Syria has recently expressed interest in resuming stalled peace talks.