"The Marines of Camp Pendleton are serving our nation with valor and integrity," Mr. Bush told a cheering crowd of Marines clad in tan-and-green camouflage uniforms.
He said the bravery and sacrifice of the troops has made America safer.
"You see, the terrorists understand what is at stake. They know they have no future in a free Iraq," said the president, who donned a tan military-style jacket with epaulets.
"They know democracy will give Iraqis a stake in the future of their country," Mr. Bush said. "When Iraqis choose their leader in free elections, it will destroy the myth that the terrorists are fighting a foreign occupation and make clear that what the terrorists really are fighting is the will of the Iraqi people."
More than 200 U.S. troops from units based at Camp Pendleton have died since the beginning of Iraqi Freedom in March 2003, according to a Defense Department casualty count.
The camp is headquarters for the 1st Marine Expeditionary Force, which has more than 21,000 men and women serving in Iraq and neighboring countries. Among their missions, Camp Pendleton Marines were among the thousands of U.S. and Iraqi troops that fought recently to secure the insurgent stronghold of Fallujah.
"How are you all?" asked the president, as he went through the cafeteria line in a mess hall, where he had lunch with troops. He emerged from the line carrying a plate of beef, noodles and rice. Mr. Bush also planned to meet with families of servicemen.
Speaking earlier on the 63rd anniversary of Pearl Harbor, Mr. Bush suggested ways Americans can actively support the troops.
Several options include a Defense Department program called "America Supports You," designed to showcase support for the military from individuals, businesses and groups as a way of encouraging others to do the same.
The ongoing insurgency in Iraq and upcoming elections on Jan. 30 dominated the president's meeting at the White House on Monday with Iraqi interim President Ghazi al-Yawer. Postponing the election, both leaders said, would amount to giving a concession to insurgents.
In May 2003, Mr. Bush flew off the coast of San Diego to the deck of the aircraft carrier USS Abraham Lincoln where he declared an end to major combat operations in Iraq under a banner proclaiming "Mission Accomplished." The event, less than two months after the invasion of Iraq, was roundly criticized when U.S. involvement in Iraq turned more violent, American deaths continued to mount and U.S. forces failed to find weapons of mass destruction, the main rationale for the war.
More than 1,200 members of the U.S. military have died since the beginning of the Iraq war in March 2003, almost 1,000 of them as a result of hostile action, according to an Associated Press count.