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President Obama announced Thursday that the United States has committed an "immediate investment" of $100 million to help with the relief and recovery efforts in Haiti in the aftermath of its devastating earthquake.

He said that fund -- to cover everything from food to medicine to equipment -- would grow in the coming year and encouraged Americans to donate toward the relief efforts as well.

"This is one of those moments that calls out for American leadership," Obama said. "We need to summon the tremendous generosity and compassion of the American people."

To the Haitian people, Obama said, "America stands with you. The world stands with you. ... Help is arriving. Much, much more help is on the way."

U.S. troops, ships and supplies are either in or on their way to Haiti to join up with international relief teams that have pledged help. The 7.0 magnitude earthquake did untold damage to the island, but casualties are feared to be at least in the tens of thousands.

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The USS Carl Vinson, an aircraft carrier, is on its way and expected to arrive on Friday. The ship is carrying 19 helicopters and has several dozen hospital beds, three operating rooms and a water purification system on board.

Two-thousand Marines are also leaving for Haiti on an amphibious assault ship equipped with disaster relief supplies and hovercrafts that can operate on land and water. Three-thousand troops from the Army's 82nd Airborne will begin arriving Thursday. And the hospital ship USNS Comfort is expected to arrive by Jan. 22. It is equipped with 250 hospital beds and 12 operating rooms.

Earlier, Secretary of State Hillary Clinton said the United States is providing the "glue" to hold together Haiti, explaining that the country is suffering from a government vacuum as aid pours in from around the world.

"It is beyond our comprehension as yet," Clinton told Fox News.

The government in Haiti was hit especially hard. The presidential palace collapsed into itself and the country's parliament building was destroyed, trapping the Senate president inside. Clinton said the United States and other nations are stepping in to fill that void and help the Haitians "piece together governmental authority" again.

"The government's been destroyed. They have no communication system. The president did get out alive, but most of his government is unaccounted for," Clinton said.

"The United States is providing a lot of the glue that is keeping people communicating, working together, as we try to assert authority, reinstate the government and begin to do what governments have to do to rebuild and reconstruct this damaged country," she said.

Clinton said United Nations peacekeeping troops will be providing "law and order."

"We're going to be on the ground in force and we're going to do everything we can to help alleviate this," Clinton said.

Fox News' Justin Fishel contributed to this report.