In a pushback against the Trump administration's protectionist rhetoric, 11 nations in the Trans-Pacific Partnership trade deal have agreed on Sunday to proceed without the U.S.

The 11 nations met on the sidelines of the Asia-Pacific Economic Cooperation (APEC) meeting for trade ministers in Hanoi and agreed to assess options to bring the deal into force "expeditiously."

"These efforts would address our concern about protectionism, contribute to maintaining open markets, strengthening the rules-based international trading system, increasing world trade, and raising living standards," the group said in a ministerial statement on Sunday.

The group said it aimed to complete the assessment before it meets again on the margins of the APEC Economic Leaders' Meeting in mid-November in Vietnam.

TPP had been considered all but dead after U.S. President Donald Trump pulled the U.S. out of the pact, a broad 12-nation trade deal, which he claimed was a "disaster" that would hurt U.S. manufacturing.

Although Japan's Prime Minister Shinzo Abe had initially said that the TPP would be "meaningless" without the U.S., more recently, Japanese officials had begun to second calls from Australia and New Zealand to proceed without the U.S.

New Zealand Trade Minister Todd McClay has spent much of this year on the road, selling the plan to keep the agreement alive to partners who worried the absence of the U.S. wouldn't make the pact worthwhile.

"New Zealand's never thought that the agreement was dead," said McClay in a recent interview with CNBC. "One country decides not to go ahead, but it's still a high quality agreement and a common set of rules across the Asia Pacific."

Japan, for one, had expended a lot of political capital on reforms needed to be a part of the deal and other countries also hadn't wanted to walk away from years of work negotiating the pact.

Among representatives of the TPP countries, Paulina Nazal Aranda, general director of international economic affairs at Chile's Ministry of Foreign Affairs, told CNBC on Sunday that the TPP-11 were united in the view that the pact was a good agreement.

"We are clear that it's going to bring benefit to our society for farmers, for families, for SMEs, for youth, for women," she said.

She expected the group would agree to fine-tune the deal to compensate for the U.S.'s absence.

"The main idea is not to reopen the complete negotiations. It's because there is a consensus that the original TPP responded to a situation that all of us were willing to comply [with] from the beginning," she said.

Echoing that view, Steven Ciobo, Australia's Minister for Trade, Tourism and Investment, told CNBC on Sunday, "There's a general consensus that we can't start unraveling it all. We've got an agreement; we're at the starting line and that's a very good basis from which we can build."

He noted that multi-lateral deals were always a "fruit salad" and there would be hurdles as each country would need to recalibrate their expectations for the U.S.'s absence from the deal.

But he added, "There's a real clarity among the 11 of us that there are real benefits in the TPP that we want to try to capture."

Whether U.S.-centric provisions are removed from the agreement may be a key sticking point.

Japan was one of only two countries — New Zealand was the other — that had already ratified the TPP and removing the U.S.-centric provisions may require the deal to pass through its Diet once again.

Keeping the provisions in the deal may also make it easier for the U.S. to change its mind and rejoin at a later date.

Both Ciobo and Aranda said they would welcome the U.S. back into the fold.

But at a news conference in Hanoi after the TPP-11 announcement, U.S. Trade Representative Robert Lighthizer said, "The United States pulled out of the TPP and it's not going to change that decision," Reuters reported.

He added that Trump has decided bilateral negotiations would be preferable to multi-lateral ones for the U.S., the Reuters report said.

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