SAN DIEGO  >> Republican presidential candidate Mitt Romney promised Monday to maintain an American military "with no comparable power anywhere in the world."

The likely Republican presidential nominee faced a San Diego crowd estimated at 5,000 in what was billed as a Memorial Day service paying tribute to the nation’s war dead, not a campaign rally. But without naming his general election rival, Romney drew clear contrasts with President Barack Obama on the issue of defense.

The Democratic president has proposed reducing the size of the military following the end of the U.S. combat role in Iraq and plans to removes troops from Afghanistan at the end of 2014.

"We have two courses we can follow: One is to follow in the pathway of Europe, to shrink our military smaller and smaller to pay for our social needs," Romney said outside the city’s Veterans Memorial Center and Museum. "The other is to commit to preserve America as the strongest military in the world, second to none, with no comparable power anywhere in the world."

Across the country in Washington, Obama marked the solemn holiday with remembrances at Arlington National Cemetery, and later at the Vietnam War Memorial marking the 50th anniversary of U.S. involvement in Vietnam.

He noted that for the first time in nine years "Americans are not fighting and dying in Iraq. After a decade under the dark cloud of war, we can see the light of the new day on the horizon."

The candidates’ comments underscored the political and practical effects the presidential contest could have on America’s role in the world.

A new Gallup survey found that veterans prefer Romney over Obama by a double-digit margin, 58 percent to 34 percent. That voting bloc, consisting mostly of older men, makes up 13 percent of the adult population.

Obama won the presidency handily four years ago while losing veterans by 10 points to Sen. John McCain, a former Navy pilot. Neither Obama nor Romney served in the military. Romney, 65, did not serve in Vietnam. His campaign says he received deferments for his Mormon mission to France and academic studies. He later entered the draft, but his number was not called, a spokesman said. Obama, 50, was a child during the Vietnam conflict.

In San Diego, Romney was joined by McCain, a Vietnam veteran who spent more than five years as a prisoner of war. McCain said that Romney "I believe, is fully qualified to be commander in chief."

Romney noted that he visited Afghanistan and Iraq during his term as Massachusetts governor. But he has limited foreign policy experience.

Still, Romney has been critical of Obama’s plans to reduce the military, in addition to the administration’s policy toward Syria’s handling of the uprising against President Bashar Assad’s government.

In a written statement Sunday, Romney said Obama "can no longer ignore calls from congressional leaders in both parties to take more assertive steps in Syria." Romney said the current approach has only given Syrian leaders more time to crackdown on protesters.

World leaders blame the Syrian government for the weekend killing of more than 100 people, including 49 children, following peaceful protests.

"I wish I could tell you that the world is a safe place today. It is not," Romney said Monday, ticking off a list of threats including Iran, Pakistan, China, Russia, Venezuela and Mexican drug cartels. He did not mention Syria.

Romney said America’s military might is needed "not so that we just win wars, but so we can prevent wars."

"A strong America is the best deterrent to war that has ever been invented," he said.