When Vietnamese prime minister Nguyen Xuan Phuc travels to the United States later this month, he will be the first national leader from Southeast Asia and the third from an Asian—but not Middle Eastern—country after Japan’s Prime Minister Shinzo Abe and Chinese president Xi Jinping were hosted by President Donald Trump. Although this does not mean that Vietnam is the third most important country in the region for the United States, it says something about the eagerness with which Hanoi and Washington, DC are reaching out to each other and the priority each enjoys in the agenda of the other.

The United States and Vietnam have important economic and security issues to discuss. With $32 billion of bilateral-trade surplus, Vietnam ranked sixth among the countries that contributed to the United States’ $502 billion trade deficit last year. With ideological ties to North Korea, Hanoi can play a role in Washington’s effort to isolate and pressure the emerging nuclear-armed state. And stretching along the western coast of the South China Sea, Vietnam holds a key to the regional balance of power. After the U.S. withdrawal from the Trans-Pacific Partnership (TPP), Hanoi is eager to know what the Trump administration can offer instead of that multilateral-trade agreement. The Vietnamese are also nervous about the possibility that Washington may trade its interests in the South China Sea for Chinese cooperation in taming North Korea.

While these hot issues make Prime Minister Phuc’s trip desirable, it is a new level of U.S.-Vietnam relations that makes it possible. Without this new level, Vietnam would not have sent one of its top leaders and the U.S. president would not have cleared his schedule for a visit from Vietnam at this early stage. Understanding the underlying forces that have formed the plateau on which the U.S.-Vietnam engagement operates is a key to making sound policy on Vietnam. To this end, let’s first review the trajectories of U.S. policy toward Vietnam as well as those of Vietnam’s policy toward the United States.

U.S.-Vietnam Relations Viewed from Ten Thousand Feet

Once a place where three million Americans fought a decade-long war, Vietnam was relegated to a low priority in U.S. foreign policy during the 1980s and 1990s. In this long period, noted Raymond Burghardt, U.S. ambassador to Vietnam from 2001 to 2004, “the U.S. approach to Vietnam was separate from any strategic plan for the East Asia region.” The restoration of diplomatic relations with Vietnam in 1995 was an enormous landmark in the bilateral relationship, but it was not a major turning point in the United States’ approach to Vietnam. As Burghardt observed, bilateral ties strengthened in the late 1990s with the focus turned toward economic opportunities, but the progress moved at a slow pace.

A major turning point in the United States’ approach to Vietnam took place in 2001, when the George W. Bush administration brought in a more critical view of China than those of the George H.W. Bush and Clinton administrations. President Bill Clinton in 1997 pledged to work toward a “constructive strategic partnership” with China, but candidate Bush in 1999 said China should be viewed as a “strategic competitor,” not a “strategic partner.” Spelling out the logic behind this belief, Condoleezza Rice, Bush’s national security advisor, argued in a 2000 article that as China had “unresolved vital interests, particularly concerning Taiwan and the South China Sea,” it “resent[ed] the role of the United States in the Asia-Pacific region” and “would like to alter Asia’s balance of power in its own favor.” Flowing logically from this geopolitical rationale was an enhanced role for Vietnam in U.S. foreign policy.

The Bush administration’s overtures to Vietnam—dialogue on strategic issues and cooperation in defense and security areas—were initially met with stiff resistance in Hanoi. After a short-lived rebalance to the West during 1987–1989, Vietnam pivoted to China in 1990, a sea change marked by the secret meeting at Chengdu in September that year between Chinese and Vietnamese Communist Party chiefs and heads of government. While reformers in the Vietnamese regime pursued U.S. ties as a doorway to the world and a counterweight to China, conservatives were adamant that China was an ally and America an adversary. In 1990 the balance of power between the two blocs tilted decisively in favor of the conservatives. As a result, Vietnam remained near the Chinese orbit and was careful not to veer close to the equidistant line between the two great powers. At his visit to China in December 2001, Vietnam Communist Party chief Nong Duc Manh vowed to oppose “hegemonism,” repeating the Chinese slogan for a fight against U.S. role and power. This was the first time that the anti-U.S. mantra appeared in a joint Sino-Vietnamese statement; but it was also the last.

The U.S. invasion of Iraq in 2003 triggered a radical change in Vietnam’s strategic assessment. In less than fifty days, a regional power in the Middle East collapsed under the weight of U.S. military power. Vietnam’s regime conservatives woke up after the conquest realizing that they were living in a unipolar world with the United States at the top. Officials in Hanoi asked me seriously at that time whether Vietnam or North Korea would be the next target. In July 2003, the Central Committee of the Communist Party of Vietnam passed a new national-security strategy (usually known as Resolution 8) that removed ideology as the key for determining friend and foe. Hanoi adopted more pragmatic criteria, according to which a foreign state was a “partner of cooperation” (đối tác) or a “target of struggle” (đối tượng) contingent on its attitude toward Vietnam’s goals, not its ideological orientation. Now the reformers’ pursuit of a strategic partnership with the United States was no longer unthinkable and their view of China as a strategic competitor no longer a taboo. The 2003 strategy also made possible the move toward the equidistant line between China and the United States. In the second half of the year, as Ambassador Burghardt recalled, “Vietnamese leaders informed us they would now welcome major steps that they had resisted for years.”

The 2003 turning point in Vietnamese foreign policy paved the way for the country to fully join the U.S-led international order. Until the second half of 2003, negotiations on Vietnam’s accession to the World Trade Organization (WTO) moved at a snail’s pace because conservatives who viewed the WTO as a U.S. scheme to turn Vietnam into a capitalist country were able to block them. After the 2003 strategy, Hanoi accelerated the negotiation and quickly joined the group in 2006. Vietnam became a globalization enthusiast and in 2008 it readily accepted the Bush administration’s offer to join the Trans-Pacific Partnership, a U.S.-led free-trade arrangement with even more transformative effect than the WTO.

Starting in the late 2000s, increased Chinese challenges, particularly Beijing’s assertiveness in the South China Sea, gave a new impetus to the emerging U.S.-Vietnam partnership. A year after her July 2010 declaration at the Association of Southeast Asian Nations Regional Forum in Hanoi that “the United States has a national interest” in the South China Sea, Secretary of State Hillary Clinton laid out a new U.S. strategy, often called the “pivot,” in which the United States aspired to develop a strategic partnership with Vietnam. During her trip to Vietnam in July 2012, Clinton made a profound gesture of friendship by inviting Communist Party chief Nguyen Phu Trong, who held no government position, to the United States. The Americans hoped at that time that Trong’s unprecedented visit would be made right in 2013.

But conservatives in Hanoi were able to torpedo the preparation for Trong’s trip. What Vietnam’s reformers and their American counterpart could reach in 2013 was not the Communist Party chief’s visit to the United States but one by President Truong Tan Sang, which culminated in a joint statement of the U.S.-Vietnam Comprehensive Partnership. It would take a major act of Chinese provocation to remove the roadblocks set up by the conservatives.

In the summer of 2014, China deployed its biggest oil rig, the $1 billion HYSY-981, into Vietnam’s exclusive economic zone. The incident sparked months-long intense protests from Vietnam, causing the worst crisis in Sino-Vietnamese relations since the massacre of seventy Vietnamese sailors and seizure of six reefs in the Spratly Islands by China in 1988. The oil rig crisis proved a game changer—it helped Vietnamese leaders to see China as a real opponent and America as a best friend. It was during this crisis that Hanoi decided to speed up preparations for General Secretary Trong’s U.S. trip, which would be materialized in July 2015.

President Barack Obama’s protocol-breaking hosting of Vietnam’s Communist Party chief at the White House was a path-breaking event. It sent a costly signal that convinced Vietnamese leaders of the benign nature of U.S. power regarding their communist regime. If the oil rig crisis of 2014 marked the first time that Hanoi trusted Washington more than it trusted Beijing, Trong’s U.S. trip solidified this disposition and drastically reduced Vietnamese leaders’ perception of the U.S. threat. Obama’s visit to Vietnam in May 2016, during which he completely lifted the arms embargo that the United States imposed on Vietnam for decades, added another boost to increasing mutual trust and reducing threat perception between the two former enemies.