It took Hanoi and Washington 20 years to establish diplomatic relations after the fall of Saigon. The two had labelled each other enemies and the US invoked the "Trading with Enemy Act" of 1917 on Vietnam during the war, which was extended to the whole country after the re-unification of North and South Vietnam.
After the Cold War, the two countries began taking small steps toward establishing diplomatic relations. In 1994, then US President Bill Clinton took the decision to end the trade embargo against Vietnam. One year later, Mr Clinton announced the "normalisation of relations". Even after normalising relations in 1995, US-Vietnam relations were plagued with memories from the war; different political ideologies; human rights issues including a clampdown on freedom of expression and control of the media; as well as leftover landmines and the lingering effects of Agent Orange. Although the two countries worked on their economic ties, the relationship was far from culminating into a strong friendship or an alliance. Washington continued to ban the sale of lethal arms to Vietnam and Hanoi was ideologically closer to China than America.
Jump ahead to 2010, and the rise of China being articulated through its maritime ambitions. China began to assert its claims in the South China Sea; they turned stronger and aggressive over the years. Like all rising powers through history, China too began its journey toward sea dominance.
The South China Sea (SCS) is an important trading route with critical strategic advantages. After the Scarborough Shoal standoff with the Philippines in 2012, the chances of a misunderstanding leading to an armed conflict has increased tremendously. Although the SCS is in dispute between six nations, most of the confrontations in the past five years have been between China and Vietnam, and China and the Philippines. An important development amidst rising tension was Washington's announcement of its "Pivot" or a rebalance to Asia-Pacific. While Beijing views the rebalance as a contain-China policy, Washington maintains that the Asia-Pacific has always been an important region in US policies and the pivot is a means to strengthen American alliances and build new relationships.
In this background, Vietnam and the US have found common ground, helping them move past the war and establish a stronger relationship. The need to balance an assertive China created the option for communist Vietnam to look toward Washington. If Vietnam began wondering about such a possibility, Washington took the steps to materialise it.
The US, in October 2014, partially lifted its arms embargo on Vietnam. The easing of the ban now allows Vietnam to acquire maritime surveillance and security-related systems. This was a clear indication of Washington's commitment to help Vietnam strengthen its maritime capabilities. There was interest from both sides in developing the security aspect of the bilateral relationship, reflected through the visit of Vietnam's minister of public security, Tran Dai Quang, to Washington in March 2015, and now that of the general secretary of the Communist Party, Nguyen Phu Trong, just last week.
Mr Trong's visit is of significant importance, as the general secretary of the Communist Party is considered one of the most conservative of political leaders. His meeting with President Obama in the White House signals the dawn of a new era, one in which Washington and Hanoi will likely be working together to secure their own strategic interests in Asia. This development also marks the 40th anniversary of the end of the Vietnam War and the 20th anniversary of normalisation of US-Vietnam relations.
The joint statement at the end of Secretary Trong's visit clearly outlines the importance of maritime security in the relationship. Vietnam pledged to support and protect human rights and welcomed "United States' policy of enhanced cooperation with the Asia-Pacific region". Both countries underlined the need to resolve the SCS dispute in accordance with the UNCLOS and expressed their concerns regarding the SCS developments undermining and threatening the established peace, security and stability of the region.
The improving ties between US and Vietnam appear to be an interesting development in the current geo-political scenario. Working on maritime security and strengthening their bilateral defence ties can be win-win cooperation for Asia. This would help Vietnam gather some support in defending its maritime boundaries and the US to strengthen its "pivot". Additionally, it also opens up other avenues of cooperation among key actors in the region - in particular, an India-Vietnam-US collaboration.
New Delhi has recently shown the political will to play an active security role in the region. As India looks to engage with other key actors in the Indo-Pacific, collaboration with Vietnam and US, especially in the maritime domain, will help New Delhi establish a credible security profile. While Vietnam is one of India's strongest partners in the Western Pacific, US is a strong security provider in the Indian Ocean. Chinese presence in the Indian Ocean is a cause of concern for New Delhi and fast becoming a reality.
Possible maritime cooperation with Vietnam and the US - a collaboration unimaginable until very recent times - will strengthen India's current approach to multilateral engagement to secure its strategic interests in the Indo-Pacific.
Multilateral engagement and responsibility sharing is the best way to stabilise the changing geo-political scenario, and a stronger relationship between Hanoi and Washington will complement such a security architecture.
The writer is at the Observer Research Foundation, New Delhi