How could roosevelt agree to the atlantic charter before the united states was even at war? was he acting within his constitutional powers as president?

the tallest building in the western hemisphere and the sixth tallest building in the world

roosevelt believed that in light of the country's recent military successes, it was unnecessary to use force to achieve foreign policy goals, so long as the military could threaten force. this belief, and his strategy of “speaking softly and carrying a big stick,” shaped much of roosevelt's foreign policy.