An American aircraft carrier will visit Vietnam in 2018, the first such visit since the end of the Vietnam War, the Pentagon announced this week.

The announcement coincided with a visit between Secretary of Defense Jim Mattis and his Vietnamese counterpart Ngo Xuan Lich in Washington D.C. The historic visit of a U.S. warship is part of a growing defense relationship between the two countries as a counter to Chinese influence in the South China Sea. Mattis sees the relationship as part of ensuring freedom of navigation in the geographically significant area.

The two also discussed deepening defense cooperation, expanding naval cooperation, and increasing information sharing.

China and Vietnam have increasingly butted heads in the South China Sea. Last month, Vietnam was forced to cease drilling for oil there after diplomatic pressure from China.

The U.S. and Vietnam have been making strides over the last 20 years to renew a working relationship. That relationship started with President Clinton normalizing diplomatic relations with Vietnam in 1995, and has continued through various commercial and military initiatives by successive administrations.

Two years ago, Secretary of Defense Ash Carter visited Hanoi and spoke of “deepening our defense relationship and laying the groundwork for the next 20 years of our partnership.” His visit, and others like it, centered primarily on committing to Vietnam’s regional security. An important milestone that year was President Obama’s decision to lift the lethal arms embargo that had been maintained against Vietnam for years.

However, many American veterans of the Vietnam War are still tirelessly working in support of POW/MIA organizations dedicated to recovering and identifying the remains of thousands of a service members who are still listed as missing in Vietnam.

In a meeting with Vietnamese Prime Minister Xuan Phuc at the White House last May, President Trump had discussed an aircraft carrier visiting the country. However, this will not be the first time an American military vessel has visited Vietnam since the war. Smaller ships have made stops recently, such as when the destroyer USS John S. McCain and submarine USS Frank Cable stopped at Cam Ranh Bay last fall.