At the 2017 Asia-Pacific Economic Cooperation CEO Summit in Hanoi, United States President Donald Trump articulated a vision of America's commitment to the safety, security and prosperity of the Indo-Pacific region.

While his comments echoed those of previous presidents, officials from his administration went to great lengths to argue that his vision was a significant departure from what had gone before. Arguably the most visible point of departure is the nomenclature. Rather than the more established notion of "Asia-Pacific", the "Free and Open Indo-Pacific", or FOIP in its abbreviated form, was parlayed as a concept that better captured the growing geopolitical and geo-economic connect between the Indian Ocean and the Western Pacific.

To be sure, the FOIP is not new to the regional lexicon. In 2007, Mr Shinzo Abe had introduced the concept to describe the strategic confluence of the Indian and Pacific oceans during his first stint as prime minister of Japan. Since then, the concept has surfaced regularly in policy discussions in India, Japan, Australia and the US.

Although the FOIP was being discussed before Mr Trump came to power, it is during the Trump presidency that it is acquiring greater currency, not least because it is evidently now the cornerstone of American policy towards the wider Asian region.

Elements of an FOIP strategy have also gradually surfaced in recent times, no doubt hastened by a growing adversarial mood towards China. The Pacific Command, the oldest and largest of America's military commands, was renamed the Indo-Pacific Command in May last year.

At the end of last year, Mr Trump signed the Asia Reassurance Initiative Act, committing US$1.5 billion (S$2.1 billion) to American engagement efforts in Asia. Meanwhile, the 21/2 years of the Trump presidency have seen more freedom of navigation operations in the South China Sea than the two terms of the Obama presidency.

Nevertheless, after two years of commentary, debate and discussion, it is still not entirely clear what the FOIP is, and how it would be operationalised.

How different will it be from the "rebalance" strategy of the Obama administration? Will it fit into the present regional security architecture or restructure it? What are the implications of affixing value-laden terms such as "free" and "open" to a spatial concept? Where and how would South-east Asian states, or China, for that matter, fit in?

Against the backdrop of such lingering concerns, US Acting Secretary of Defence Patrick Shanahan took to the stage at last weekend's Shangri-La Dialogue to further elaborate on the essence of the Trump administration's strategy. Three broad points stood out from his effort to cast more light on the issue.

First, the US is a Pacific nation and remains committed to the region. This commitment is reflected in the distribution of attention, budget and resources to the Indo-Pacific as its geographical focus and "priority theatre".

Second, countries in the region must rally together and play their part to collectively build a "shared security order".

Third, actors seeking to undermine the rules-based international order pose the greatest long-term threat to the vital interests of states in the region.

To accent these priorities, Mr Shanahan's speech was accompanied by the official release of the Indo-Pacific Strategy Report by the US Department of Defence, which outlined Washington's strategic outlook and priorities in the region, and detailed the policies that would flow from this.

THE FOIP STRATEGY - A MIXED BAG

On a positive note, the FOIP should be viewed for what it is - an effort by the US to remain engaged in the region in pursuance of its national interests. This effort on the part of Washington to signal its intent should not be downplayed, particularly given the nature of Trump administration foreign policy as seen from a broader perspective. It is already well documented how Mr Trump is withdrawing the US from a host of multilateral organisations and reconsidering - in some cases, even reneging on - international commitments and agreements.

It is against this climate that the FOIP stands out, simply for the fact that it suggests a serious effort on the part of the Trump administration to think strategically about engaging the region.

This is not to say, however, that there is not a need for still greater clarity regarding the FOIP. Indeed, there is, for at least three reasons.

First, while greater American attention is doubtless welcome in the region, regional states have always laboured the point that US policy should not be shaped solely by competition with China, nor should it take too overt a militarised form. The fact that, more than any other agency, it is the US Department of Defence that appears to be driving the FOIP strategy is something that would discomfit regional states.

Second, while the salience of networks and partnerships was repeatedly stressed, both in the strategy report and in Mr Shanahan's speech, this has not quite dovetailed with Washington's own approach on other fronts.

The manner in which the US has conducted economic and trade relations with some of its closest regional friends and allies - dialling up pressure on Japan and South Korea over trade issues, and on Singapore, Malaysia and Vietnam over currency policy - is puzzling in this regard.

Put simply, Washington's posturing on the trade and economic front does not accord with the objective of deepening and strengthening security networks and partnerships.

Likewise, the stress on partnerships to reinforce the rules-based international order would have rung less hollow if the White House was not itself challenging and undermining the said order through its open disdain for multilateralism and withdrawal from crucial initiatives that underpin it.

Third, there is the proverbial elephant in the room in the form of China. Publicly, American officials are quick to quell suspicions that the FOIP resembles a containment strategy. Privately, however, they tend to be less circumspect.

Yet, even though anxieties still obtain in regional states regarding Chinese intentions, they are certainly not prepared to bear the economic cost of aligning themselves with any overt attempt to contain China, especially when Beijing is itself investing heavily to improve relations with the region.

Moreover, even if the effort to call China out where its activities undermine the rules-based international order was necessary, it is equally important that clear signals be sent about the potential avenues for cooperation in order to avert the onset of a new Cold War.

This final point suggests that ultimately, the FOIP is a strategy that both shapes and is shaped by Sino-US relations.

Indeed, the question has never been about whether Washington and Beijing should nurture a constructive relationship with each other. Neither set of leaders would disagree with that proposition. Rather, the real question is what the terms of such a relationship are, and who gets to define the terms.

Here is where the rubber hits the road, and where there is fundamental divergence.

Whether the FOIP can assuage concerns that Sino-US relations are lurching towards a zero-sum game by providing opportunities for cooperation, or actually hastens the process, only time can tell.

•Joseph Chinyong Liow is dean, College of Humanities, Arts, and Social Sciences, Tan Kah Kee Chair in Comparative and International Politics, and professor, S. Rajaratnam School of International Studies (RSIS), Nanyang Technological University. Amanda Trea Phua is senior analyst in the US Programme at RSIS.