WASHINGTON-- US President Barack Obama on Monday reflected the "hard lessons" of the Vietnam War, calling it "one of the most painful chapters in our history," as the country begins a 13-year commemoration that marks the 50th anniversary of major US engagement in the war.

Speaking during a ceremony at the Vietnam War Memorial in downtown Washington, Obama said the anniversary can remind the country to never forget "the lessons of that war", including when sending soldiers into harm's way, adding "we will always give them a clear mission; we will always give them a sound strategy."

"We will resolve that leaders will be candid about the risks and about progress -- and have a plan to bring our troops home, with honor," said the president.

He continued to mark "the costs of war, including the terrible loss of innocent civilians -- not just in Vietnam, but in all wars," noting "war itself is not glorious. We hate war."

"Because of the hard lessons of Vietnam," said Obama, "we now use American power smarter, we honor our military more, we take care of our veterans better."

The ceremony kickstarted a 13-year commemoration of the unpopular Vietnam War, during which over 58,000 US soldiers lost their lives, and as Obama puts it, a war "some have called... a scar on our country."

As the United States commemorates the Vietnam War, Obama is also taking the day to remind voters he brought an end to the Iraq War, and is winding down the Afghanistan War. During a speech he gave earlier in the day, Obama said at the Arlington National Cemetery that "after a decade under the dark cloud of war, we can see the light of the new day on the horizon."

"For the first time in nine years," he said, "Americans are not fighting and dying in Iraq. We are winding down the war in Afghanistan, and our troops will continue to come home."

He also echoed the theme of his Vietnam War speech at Arlington Cemetery, promising to never send the military into harm's way "unless it's absolutely necessary," and when he does, he would give the troops "a clear mission and the full support" of a nation.

Obama also used the opportunity to promise better care for veterans, a crucial voting bloc in the upcoming election, saying "let's resolve to take care of our veterans as well as they've taken care of us -- not just talk, but actions," vowing to give better healthcare, job opportunities and housing help to veterans.

Obama is competing with Republican candidate Mitt Romney for veterans' votes, and polls show he lagged behind.