U.S. President Donald Trump on Friday put his "America First" mantra and bilateral trade deals with Asian nations on the basis of "fairness and reciprocity" at the core of his efforts to advance what he describes as "a free and open Indo-Pacific" region.

Instead of asserting U.S. leadership in the region in concrete terms in a closely watched speech in Danang, Vietnam, Trump indirectly criticized regional free trade initiatives such as the Trans-Pacific Partnership, a China-excluding pact from which the United States withdrew in January.

"I will make bilateral trade agreements with any Indo-Pacific nation that wants to be our partner and that will abide by the principles of fair and reciprocal trade," he said at a business event on the sidelines of a summit of the Asia-Pacific Economic Cooperation forum in the central Vietnamese city.

But as if to snub Trump's call for "a renewed partnership" with the Indo-Pacific region through "robust" trade ties, Japan and 10 other remaining TPP members agreed in principle on Thursday to implement the regional free trade agreement without the United States.

Without singling out countries such as China, Trump accused other countries in the Indo-Pacific -- a vast area covering the Indian Ocean, the Western Pacific and the countries that surround them -- of engaging in unfair trade practices, market access restrictions, subsidized goods and predatory industrial policies.

"We are not going to let the United States be taken advantage of anymore," he said. "I am always going to put America first the same way that I expect all of you in this room to put your countries first."

In an apparent criticism of multilateral free trade agreements like the TPP, Trump said, "What we will no longer do is enter into large agreements that tie our hands, surrender our sovereignty and make meaningful enforcement practically impossible."

Through a bilateral framework, the United States will seek to address intellectual property theft, subsidizing of industries through state-owned enterprises, as well as cyberattacks, corporate espionage and other anti-competitive practices, with trading partners, according to the U.S. leader.

"We expect that markets will be open to an equal degree on both sides, and that private industry, not government planners, will direct investment," he said.

Touching on security issues, Trump reiterated his call for every responsible nation to jointly pressure North Korea to force it to abandon its nuclear and missile programs.

"The future of this region and its beautiful people must not be held hostage to a dictator's twisted fantasies of violent conquest and nuclear blackmail," he said.

In an apparent reference to China's assertive territorial claims in the East and South China seas, as well as its increased military presence in the Indian Ocean, Trump urged Indo-Pacific nations to respect the rule of law and freedom of navigation and overflight, including open shipping lanes.

Aside from China's attempts to undermine the Japanese administration of the Senkaku Islands in the East China Sea, Beijing has militarized outposts in disputed areas of the South China Sea, where it is pitted against Brunei, Malaysia, the Philippines, Vietnam and Taiwan in territorial disputes.

Trump arrived in the central Vietnamese city earlier Friday after visiting Japan, South Korea and China.

During their meeting in Tokyo on Monday, Trump and Japanese Prime Minister Shinzo Abe agreed to promote the rule of law and other basic values for the Indo-Pacific region.

Trump is on the fourth leg of his five-nation Asian tour, his first official trip to the region since taking office in January that will next take him to the Philippines.