President George W Bush announced Wednesday that the US military was heading for Georgia to deliver humanitarian aid, establishing an American presence in the region and sending a clear signal to Russia that it is time for the conflict to end. The first C-17 cargo plane landed late Wednesday in Georgia, and more planes and US Navy vessels were on the way to provide food, medicine and other supplies in a ''vigorous and ongoing'' effort to demonstrate ''solidarity'' with the Georgian people, Mr Bush said.

Washington's plans don't include sending combat aircraft or warships, but the move brings the US military into close proximity with Russian military forces, which are reportedly continuing to advance ever deeper into Georgian territory despite a declared cease-fire.

''It has the impact of saying to Russia, 'Enough is enough','' said US army retired general William Nash, now an adjunct scholar at the Council on Foreign Relations in Washington. ''It is time for everybody to calm down and start the political process.'' The delivery of relief supplies ''places Americans as a distinct party to the circumstances in Georgia''.

''Future Russian action after we become present could endanger Americans. And that can be seen as a trip wire for further US action,'' Mr Nash said.

The conflict began on Aug 7, when President Mikheil Saakashvili ordered Georgian troops into the breakaway region of South Ossetia to quell attacks by separatists fighters backed by Moscow.

Russia responded with a massive military assault deep into Georgian territory, quickly reaching beyond disputed South Ossetia. Fighting quickly spread to Abkhazia, a second Russian-backed secessionist region in the former Soviet republic. ''There were provocations on all sides,'' White House spokeswoman Dana Perino said.

The US presence in Georgia will serve more as a ''conflict prevention measure'' rather than putting Washington on course for a military confrontation with its former Cold War rival, Mr Nash said.

The US military has already been stretched to the breaking point with the continuing missions in Iraq and Afghanistan.

The White House said that Mr Bush chose the military to lead the operation because it is most capable of rapidly responding to the crisis and mobilising shipments of goods to Georgia. The military generally takes the lead role when the US responds to disasters around the world.

US Secretary of State Condoleezza Rice told reporters hours after Mr Bush's announcement that the US mission is purely limited to meeting humanitarian needs, and she rejected suggestions by pro-Western Georgian President Saakashvili that the US military would secure Georgia's sea ports and airports.

''It is not the intention of the United States in some way to take control of facilities, port facilities or the like,'' Ms Rice said.

Bush sternly said in a short statement at the White House that he expects Russian cooperation to ensure that the key routes remain open, so humanitarian supplies can flow into the country devastated by the Russian assault.

Ms Perino brushed aside questions of how Washington might respond if Russia interferes with humanitarian missions or refuses to halt the military campaign.

''That's way premature and hypothetical and speculative, and nothing that I would comment on,'' she said, but added that no options were ruled out.

Meanwhile, the United States has begun contemplating ways to punish Russia's massive military response, which Ms Rice described as going ''well beyond the bounds of the conflict in South Ossetia''.

She refused to answer questions about whether Washington will move to throw Russia out of the G8, a group of wealthy industrialised nations. Mr Bush, however, warned that Russian actions in Georgia have damaged Moscow's standing in the world and jeopardised its role in diplomatic and global economic affairs and institutions.

''Russia is putting its aspirations at risk by taking actions in Georgia that are inconsistent with the principles of those institutions,'' Mr Bush said.

The Pentagon confirmed Wednesday that the US Navy has dropped plans to join naval exercises hosted by Russia later this month. dpa