President Donald Trump on Monday unveiled in the most concrete terms to date his "America First" foreign policy, blasting the actions of previous administrations on immigration, the Iran nuclear deal and trade pacts, among others.

His new policy casts China and Russia as elevated global competitors and vows to protect US interests over those of the larger global community.Spelling out his National Security Strategy, Trump declared a new era of American foreign engagement had been ushered in by his election.You embraced new leadership and very new strategies and also a glorious new hope," Trump said Monday afternoon.

Past presidents "forgot whose voices they were to respect and whose interests they were supposed to defend," Trump said.

Both Russia and China are described as "revisionist powers" who "want to shape a world antithetical to US values and interests" in the strategy document.

Toward China, Trump adopts a combative stance that challenges Beijing's unfair economic practices and its attempts to exert control over islands and waterways in the South China Sea.

And he paints Russia as a destabilizing force intent on returning to Cold War-era spheres of influence that could divide western allies.

The doctrine envisages a world in constant rivalry for economic and security influence. At the same time, Trump downplayed global agreements signed during past administrations meant to bring the world's nations into better agreement on issues like trade and climate change.