President Obama's announcement Monday that the U.S. could start selling weapons to its former enemy Vietnam means changes ahead for troopssailors.

The president made the announcement at a Hanoi press conference, which ended a half-century ban on U.S. arms sales to Vietnam, putting to rest one of the last foreign policy vestiges of one of the most divisive wars in American history.

Five Here are things service members should know:

1. More visits. Port calls in Vietnam are likely to increase, something Obama previewed in the press conference yesterday. The president hinted at increased military-to-military cooperation for humanitarian assistance coordination, which would lead to more troops and sailors visiting and that could mean more ships making stops in Vietnam.

"There may be occasions in which that means more U.S. vessels might visit but I want to emphasize that we will do so only at the invitation and with the full cooperation of the Vietnamese government, fully respecting their sovereignty and their sensitivities," he said.

U.S. Pacific Command head Adm. Harry Harris told the Senate Armed Services Committee in February that he was pushing for more port visits in the country and that Vietnam was receptive to greater cooperation.

2. Strategic hotspot. One of the reasons Vietnam has fought so many wars is because of its unique geography, which is part of what makes it a valuable U.S. partner. and its partly that geography that has the brass eager to deepen its relationship with the country. It borders the disputedhotly contested South China Sea and features one of the key deep-water ports in the the whole region: Cam Ranh Bay. That facility used to be a major U.S. operating base during the Vietnam War and Russia leased and expanded it throughout the 1980s and 1990s before leaving packing up in 2002.

"Cam Ranh Bay is a crucial port in the region that strategic planners have missed since the day we left," said Jerry Hendrix a retired Navy captain and expert at the Center for a New American Security.

Vietnam just opened an international port facility there and Pacific Fleet head Adm. Scott Swift told Navy Times in early May that he was looking to that facility as a way to increase U.S. engagement in Vietnam. Read more about that here.

3. Boots on the ground. With weapons sales to Vietnam on the docket, that also means the possibility of troops deploying to Vietnam as trainers to get the Vietnamese up to speed on their new gear.

The State Department is already working on an initiative that could bring ground troops to Vietnam. The Vietnam Peacekeeping Center is a joint effort with the Vietnam and the U.S. It's a training center designed to help boost Vietnam's ability to contribute to U.N. peacekeeping missions.

One thing the Vietnamese are interested in is the U.S. military's advanced field medicine capabilities that have saved thousands of lives during the wars in Iraq and Afghanistan.

4. China is watching. China and Vietnam have a tenuous relationship at the moment, mostly due to China's aggressive pursuit of its claims to 90 percent of the South China Sea. The two countries have fought each other in the past over their overlappingdisputed claims in the region and China's island building and aggressive tactics in the region are making them nervous. 

For the U.S., that's an opportunity to make an old enemy a new friend. But President Obama made clear that he sees it as the natural end of a long process of normalizing relations with Vietnam.

Don't be fooled, however. With Defense Secretary Ash Carter's recent announcement that more U.S. troops and aircraft are going to be rotating through the Philippines, this new action on the other side of the South China Sea will have China concerned.

5. Changing times. The lifting of the arms sales ban underscores how much things have changed in the last half century. Adm. Bob Natter, a former U.S. 7th Fleet commander and a Silver Star recipient for bravery in the Vietnam War, captured it succinctly:

"Times change and we've got to adjust with the times," Natter said. "We have more in common with Vietnam today than separates us, at least on a strategic level."