WASHINGTON — President Bush said today he is skeptical that Moscow is honoring a cease-fire in neighboring Georgia, demanding that Russia end all military activities in the former Soviet republic and withdraw all its forces.

“The United States stands with the democratically elected government of Georgia and insists that the sovereignty and territorial integrity of Georgia be respected,” Mr. Bush said sternly during brief remarks in the White House Rose Garden.

“To demonstrate our solidarity with the Georgian people,” the president announced that he was sending Secretary of State Rice to Paris to assist the West’s diplomatic efforts on the crisis, and then to the Georgian capital of Tbilisi.

He also announced that a massive American humanitarian effort was already in progress, and would involve American aircraft as well as naval forces. An American C-17 military cargo plane loaded with supplies is already on the way, and Mr. Bush said that Russia must ensure that “all lines of communication and transport, including seaports, roads, and airports,” remain open to let deliveries and civilians through.

“To begin to repair the damage to its relations with the United States, Europe and other nations and to begin restoring its place in the world, Russia must keep its word and act to end this crisis,” Mr. Bush said.

The president spoke amid a fast-moving chain of events, with Ms. Rice canceling a planned morning news conference and the White House scrubbing its regular morning briefing with reporters. Despite extensive intelligence resources and deep ties to the Georgian military that America has trained, the administration has struggled to determine what’s happening on the ground, for instance whether Russia is pushing deeper into Georgia or threatening Tbilisi.

Neither the president nor his Cabinet has answered questions on the record about the 6-day-old crisis except for remarks that Mr. Bush made in a television interview on the sidelines of the Olympic Games in Beijing.

Mr. Bush spent the morning meeting with his national security team in the White House Situation Room, the nerve center for monitoring international developments. He talked by telephone with Georgia’s embattled president, Mikhail Saakashvili and with President Sarkozy of France, who traveled to both Tbilisi and Moscow and is leading a European Union initiative to bring about peace there.

The administration and its allies are debating ways to punish Russia for its invasion of Georgia, including expelling Moscow from an exclusive club of wealthy nations — the G-7 — and canceling an upcoming joint NATO-Russia military exercise.

But it has become increasingly clear that the West may have little leverage to influence Moscow’s decisions. Mr. Bush held out no specific punishment.

“Russia has sought to integrate into the diplomatic, political, economic, and security structures of the 21st century. The United States has supported those efforts,” he said. “Now Russia is putting its aspirations at risk by taking actions in Georgia that are inconsistent with the principles of those institutions.”

Mr. Saakashvili called the Western response inadequate. “I feel that they are partly to blame,” he said. “Not only those who commit atrocities are responsible … but so are those who fail to react.”

The tiny, poverty stricken nation of Georgia has staked its future on leaning West and joining NATO is one of its key goals. Bush has supported this move, but alliance leaders put the requests from Georgia, as well as another ex-Soviet republic, Ukraine, on hold in April for fear of upsetting relations with Moscow.

Mr. Bush, during a 2005 visit to Tbilisi, personally assured the people of Georgia that America would be its unflinching ally.

“The path of freedom you have chosen is not easy, but you will not travel it alone,” Mr. Bush said in an address to a crowd of thousands in Freedom Square. “Americans respect your courageous choice for liberty. And as you build a free and democratic Georgia, the American people will stand with you.”

The Russian operation began after Georgia last week tried to secure control over South Ossetia, a breakaway region loyal to Moscow. Russia’s fierce military response expanded to Abkhazia, another separatist province, and ended up on purely Georgian soil.

Today, after Mr. Saakashvili said he accepted a cease-fire plan brokered by France that called for both sides to retreat to their original positions, and after President Medvedev said Russia was halting military action, Russian tanks rumbled into the Georgian city of Gori. Georgian officials said Gori was looted and bombed by the Russians. An AP reporter later saw dozens of tanks and military vehicles leaving the city, roaring south and deeper into Georgia.

Mr. Bush said America is concerned that Russian units have taken up positions on the east side of Gori, which allows Russia to block an east-to-west highway, divide the country and threaten the capital of Tblisi. The president said he’s also concerned that Russian forces have entered and taken positions in the port city of Poti, that Russian armored vehicles are blocking access to that port, and that Russia is blowing up Georgian vessels.

Mr. Bush said this appears to contradict Russia’s promise of a halt to military operations.

“Unfortunately we’ve been receiving reports of Russia actions that are inconsistent with these statements,” he said.

In addition, he said, “We’re concerned about reports that Georgian citizens of all ethnic origins are not being protected.”