Israel's warplanes bombed Beirut's international airport and its navy blockaded Lebanon's ports in a sharp escalation of a military campaign Thursday.
Hezbollah guerrillas fired scores of rockets from Lebanon into northern Israel in the most intense bombardment in years.
The missiles killed one woman and at least 10 others were hurt in the attack on Safed, about 13 miles (20 kilometers) from the Lebanese border, which local officials said not been hit by Hezbollah rockets since 1972.
Beirut's Rafik Hariri International Airport was forced to close after Israeli fighter jets hit all three of its runways, leaving huge craters and making them unusable.
Two other Lebanese airports were attacked Thursday morning, the Israel Defense Forces said.
The IDF gave no details, but Lebanese army sources said that the Rayak Air Base in the Bekaa Valley had been hit as well as a small military airport in Qulayaat in northern Lebanon.
Israel said it targeted the international airport in the capital's suburbs because it was a transfer point for weapons and supplies to Hezbollah, the militant group that captured two Israeli soldiers and killed eight others in raids earlier this week.
Lebanese Interior Minister Ahmed Fatfat called the airport strikes a "general act of war," saying they had nothing to do with Hezbollah but were instead an attack against the country's "economic interests," especially its tourism industry. All Beirut-bound flights are having to be diverted.
At least 45 people have been killed in Lebanon since the violence began Wednesday, Lebanon's health ministry said.
After the airport attack, planes began dropping leaflets warning residents of an impending attack on an area of southern Beirut where Hezbollah leader Hassan Nasrallah is believed to live.
If such a strike happened, Hezbollah said it would attack the northern Israeli city of Haifa, where 300,000 people live.
The U.S. Navy moved a small military tug out of Haifa after the threat.
Israel: 'We mean business'
Palestinian Authority President Mahmoud Abbas said Thursday he fears a "regional war is mounting" with Israel's two ongoing military campaigns in Lebanon and in Gaza, where forces were deployed after the capture of an Israeli soldier last moth.
"This is not our interest and will not bring peace and stability to the region," Abbas said, referring to "this [Israeli] aggression."
President Bush warned Israel to take care not to "weaken" Lebanon's government.
Bush also stressed during a visit to Germany that Syria "needs to be held to account."
Hezbollah enjoys substantial backing from Syria and Iran and is considered a terrorist organization by the United States and Israel. The group holds posts in Lebanon's government.
Israeli Security Cabinet Minister Isaac Herzog said: "We are taking strong measures so that it will be clear to the Lebanese people and government ... that we mean business."
The United Nations will send a team to the Middle East to urge both sides to use restraint, a spokesman for Secretary-General Kofi Annan said Thursday.
Israeli airstrikes were aimed at targets used by Hezbollah for storing weapons, the IDF said.
Warplanes also hit al-Manar television station because Hezbollah uses it to incite and recruit activists, the IDF said. A broadcast tower was destroyed and three people injured, but the station was able to continue broadcasting, al-Manar editor Ibrahim Moussawi said.
Israel's Cabinet authorized a "severe and harsh" response to the abduction of the two soldiers, named Thursday as Ehud Goldvasser, 31, from Nahariya, and Eldad Regev, 26, from the Haifa suburb of Kiryat Motzkin.
Hezbollah called for a prisoner exchange but, as in Gaza, Israel has rejected the call.
Hezbollah chief Nasrallah told reporters that seizing the soldiers was "our natural, only and logical right" to win freedom for Hezbollah prisoners held by Israel.
Nasrallah said the two soldiers had been taken to a place "far, far away" and that an Israeli military campaign would not win their release.
More than 70 Katyusha rockets have hit Israel in the past 24 hours, the IDF said.
In addition to the attack on Safed, missiles hit the Arab village of Carmiel in northern Israel, wounding at least 38 people, according to Israeli ambulance services.
Earlier Thursday, one woman was killed and 15 people injured in a rocket attack on Nahariya, also in northern Israel.