Asia-focused foreign and security policy analysts in Washington, many of whom have been sceptical about the Donald Trump administration's commitment to the US' Asian allies, have welcomed the allocation of US$2.5 billion (S$3.4 billion) to the 2018 Asia Reassurance Initiative Act (Aria).

Analysts noted the bipartisan support in Congress for Aria, even though the amount is not as much as proponents of US engagement in the Asia-Pacific would like.

"US$2.5 billion on its own isn't enough. It's not even near what we've provided for the European Deterrence Initiative," Ms Lindsey Ford, foreign policy fellow at the Brookings Institution's Centre for East Asia Policy Studies, said.

She told The Straits Times: "On its own, this funding can't meet the full scale of the challenges the US faces in Asia. But it represents a much-needed down payment that hopefully leads to additional funding in the years to come."

She added: "It is a welcome signal that Congress intends to put serious muscle behind an Asia strategy that has been under-resourced for years. What matters the most is whether Congress can sustain this and build on it in future."

Aria is aimed at, among other objectives, enhancing the US security presence in the Indo-Pacific, reaffirming support for the country's allies, including Japan, South Korea and Australia, supporting a deepening strategic relationship with India, and arms sales to Taiwan.

This is a "fully-funded generational US policy framework for the Indo-Pacific region that will ensure the United States remains the preeminent Pacific power for generations to come," said Colorado Senator Cory Gardner, a Republican and co-author of Aria, in an e-mail.

Senator Ed Markey, a Democrat from Massachusetts and co-author of Aria, said: "The United States is invested in Asia's success. Our government is now further empowered to advance America's interests as we witness the spread of authoritarian governance, human rights violations, and aggressive Chinese military modernisation in the region.

"The United States cannot afford to cede leadership as the country that best empowers people across the Indo-Pacific to seek freedom and economic opportunity."

Aria is a modest but significant step to signal to the region that Washington is serious about the Indo-Pacific, Dr Robert Manning, resident senior fellow at the Atlantic Council's Scowcroft Centre for Strategy and Security, told The Straits Times.

But Dr Manning said that Aria and other efforts must also be viewed against the "contrary and incoherent 'America First' doctrine pursued by President Trump, which, beginning with the US' withdrawal from TPP (the erstwhile Trans-Pacific Partnership), derides alliances and regional multilateralism writ large".

"This has sparked a sense of US retreat and abandonment among many in Asia," he added.

Dr Denny Roy, a senior fellow at the East-West Centre in Honolulu, said: "The Bill (Aria) underscores three larger phenomena: A deep and bipartisan consensus in the US on a tougher policy towards China; Washington remaining committed to not ceding strategic dominance in the region to China; (and) the difficulty of the US beating China in a contest to win regional allegiance by outspending the opponent.

"It may look more important if and when China's more grandiose (by orders of magnitude) BRI (Belt and Road Initiative) and related loans and investment generate a backlash against its transparent neo-colonial assertiveness."

The allocation of additional resources to the Indo-Pacific is a positive development, said Dr Bonnie Glaser, senior adviser for Asia and director of the China Power Project at the Centre for Strategic and International Studies in Washington.

"But such efforts to provide reassurance to the region of the US' steadfast commitment to regional security are likely insufficient to offset the damage done by contradictory Trump administration actions," she cautioned, citing the President's decision not to attend the East Asia Summit in Bangkok last month, and US demands that Seoul pay a huge sum for the continued stationing of US troops in South Korea.