TRIPOLI, Libya - The Obama administration reached out Tuesday to the Libyan rebels and said Moammar Gadhafi would "inevitably" be forced from power as the U.S.-backed NATO coalition launched a withering bombardment on the Libyan leader's stronghold of Tripoli.

The NATO air strikes struck in rapid succession shortly after midnight, setting off more than 20 explosions in the most intensive bombardment yet of the Libyan capital. Plumes of acrid-smelling smoke rose from an area around Gadhafi's sprawling Bab al-Aziziya compound in central Tripoli.

Late Tuesday, NATO hit Tripoli again, aiming at least six air strikes at the same targets and one farther away. Smoke rose from the area near Gadhafi's compound for the second night in a row. There were no immediate reports of casualties.

A U.S. official warned the Libyan ruler that the pace of the attacks would intensify. Deputy national security adviser Ben Rhodes said, "I think we want to underscore to Gadhafi that the foot is not going to come off the gas pedal," adding that "leaving is in his best interests and the best interest of the Libyan people."

With its invitation, the U.S. administration bolstered the standing of the rebel National Transnational Council, calling it a "legitimate" and "credible" body and extending an invitation for it to set up a representative office in Washington - though the overture stopped short of formal U.S. recognition.

Praising the rebel leadership, Secretary of State Hillary Rodham Clinton said that the interim council "is committed to democratic principles, their military forces are improving, and when Gadhafi inevitably leaves, a new Libya stands ready to move forward."

The international community has stepped up both the air campaign and diplomatic efforts against the regime in a bid to break a virtual stalemate between the rebels in the east and Gadhafi, who maintains a stranglehold on most of the west. NATO Secretary-General Anders Fogh Rasmussen said Tuesday in Herat, Afghanistan, that he hoped a "solution" would soon come to end the fighting in Libya.

The United States launched the international air campaign March 19 after the United Nations authorized "all necessary measures" to protect civilians after Gadhafi's brutal suppression of the popular uprising against his rule. NATO, which has taken over the air strikes, says it has been doing its best to minimize the risk of collateral damage.

Critics argue that NATO has overstepped its mandate and is trying to bring about Gadhafi's ouster. And British analysts have criticized the Obama administration for refusing to expand its military engagement in Libya.

But U.S. officials have expressed fears that cuts in military spending could hobble Britain's ability to support the United States in foreign conflicts.

Developments in the Region

Yemen: Fighters from Yemen's powerful tribes fired on government buildings, and soldiers retaliated with intense shelling as the uprising against President Ali Abdullah Saleh threatened to become a militia-led revolt after street protests and Arab mediation failed. A total

of 38 people were killed. Ten hours after the battles started, the capital of San'a was a no-man's land with heavy gunfire, mortar rounds, and artillery fire. Saleh called for a cease-fire.

Syria: The death toll from Syria's crackdown on

a nine-week uprising exceeded 1,000, a human-rights group said, and the country's opposition called for

fresh protests and clearer goals. Amar Qurabi, head of the National Organization for Human Rights in Syria, said the opposition planned a conference in Turkey to find a common voice for its antigovernment movement.

Bahrain: The Bahrain Chamber of Commerce froze ties with Iran, Iraq, and Lebanon in response to what it

sees as foreign meddling in Shiite-led protests. The move is likely to increase tension between the nation - ruled by a Sunni monarchy and home to the U.S. Navy's Fifth Fleet - and its Shiite neighbors. Amnesty International has urged the king to overturn death sentences against two people arrested during protests.

- Associated Press