Leadership over U.S. President Donald Trump's Asia policy has jockeyed between "security internationalists" such as Defense Secretary Jim Mattis and "economic nationalists" like Commerce Secretary Wilbur Ross, according to an American scholar specializing in Asian security.

"Since the beginning, the administration has been a battleground between the two groups," said Zack Cooper, a senior fellow at the Center for Strategic and International Studies, as internationalists appear to be driving security policy and nationalists advocating the "America First" approach dominant in economic affairs.

Speaking in an interview ahead of the one-year mark of Trump's presidency on Jan. 20, Cooper cited the strategy for "a free and open Indo-Pacific region" as a major product of the administration's internationalist wing and the U.S. withdrawal from the Trans-Pacific Partnership trade deal as a disappointing move by the nationalist camp.

Cooper hailed the Indo-Pacific concept -- security cooperation the Trump administration promotes with Japan, India and Australia for a rules-based order -- saying it "smartly seeks to put forward a positive vision for U.S. engagement with the region" in an apparent extension of his predecessor Barack Obama's policy of strategic "rebalance" to Asia in the face of the rise of China.

"President Trump has essentially embraced his predecessor's rebalance strategy, but dropped his positive economic agenda," he said, in reference to the TPP, a regional free trade agreement championed by Obama.

"This leaves many in Asia perplexed about how the administration can obtain a free and open Indo-Pacific while pursuing protectionist trade policies."

Propelled by economic nationalists -- including U.S. Trade Representative Robert Lighthizer and Peter Navarro, director of the White House National Trade Council -- Trump has been calling for bilateral trade deals with Asian countries as a way of reducing U.S. deficits, a move critics say reflects the nationalist camp's view of trade as "zero-sum."

"The economic nationalists want to maximize U.S. leverage by negotiating bilateral trade deals, even if this agenda undermines pre-existing security cooperation efforts, as with South Korea," Cooper said, expressing concern the administration's push to renegotiate the U.S.-South Korea FTA on better terms for Washington could weaken the bilateral alliance amid the rising nuclear threat posed by North Korea.

The internationalist camp, including national security adviser H.R. McMaster and Secretary of State Rex Tillerson, seeks to counterbalance China by boosting the U.S. economic position in the region and adopting high-standard trade agreements to reinforce existing rules and norms -- an objective Cooper said the TPP, which does not involve Beijing, "would have been an obvious fit."

Trump needs "a positive economic component" to complement the Indo-Pacific concept, the scholar said, because the administration "is likely to have limited success with bilateral trade deals since most countries in the region would prefer multilateral arrangements" such as a so-called TPP 11, a project Japan and 10 other remaining TPP signatories have agreed to promote.

According to a study by the Peterson Institute for International Economics, the original TPP would have generated global income benefits of $492 billion, including $131 billion for the United States, while TPP 11 would generate $147 billion globally, with the United States losing $2 billion by 2030.

"Bilateral FTAs cannot spur regional production networks, an important motivation for current Asia-Pacific integration," it said.

"Barring a fundamental change in its approach, abandoning TPP will leave the Trump administration without an economic component to its regional strategy," Cooper said. "In the long term, the hope will be that the United States returns to TPP or that a Free Trade Area of the Asia-Pacific emerges as a potential alternative that could be inclusive and set high standards."

He was referring to an FTA covering the 21-member Asia-Pacific Economic Cooperation forum, which groups the United States, China, as well as all 11 TPP countries including Japan, Australia and some members of the Association of Southeast Asian Nations.

Cooper said any strategy creating a free and open Indo-Pacific -- a vast area covering the Indian Ocean, the Pacific Ocean and the countries that surround them -- must be "inclusive" and provide a positive vision for how the United States, Japan and others can build greater prosperity and security for all states in the region, including China.

"The strategy will not be appealing in ASEAN countries and beyond if it is seen solely as an effort to counter growing Chinese influence," he said. "Instead, the strategy must be about strengthening the region's rules and norms to ensure that all countries can grow and prosper free from coercion and conflict."

"The question for the Trump administration is how exactly they plan to do that," Cooper said, since Asian countries are nervous about offending China over their increased reliance on it as a trading partner and investment source despite Beijing's muscle-flexing in the South China Sea and elsewhere.