"Speak softly and carry a big stick" Theodore Roosevelt famously said in 1901, when the United States was emerging as a great power. It was the right sentiment, perhaps, in an age of imperial rivalry but today many Americans doubt the utility of their global military presence, thinking it outdated, unnecessary or even dangerous.

In The Big Stick, Eliot A. Cohen-a scholar and practitioner of international relations-disagrees. He argues that hard power remains essential for American foreign policy. While acknowledging that the US must be careful about why, when, and how it uses force, he insists that its international role is as critical as ever, and armed force is vital to that role.

Cohen explains that American leaders must learn to use hard power in new ways and for new circumstances. The rise of a well-armed China, Russia's conquest of Crimea and eastern Ukraine, nuclear threats from North Korea and Iran, and the spread of radical Islamist movements like ISIS are some of the key threats to global peace. If the United States relinquishes its position as a strong but prudent military power, and fails to accept its role as the guardian of a stable world order we run the risk of unleashing disorder, violence and tyranny on a scale not seen since the 1930s. The US is still, as Madeleine Albright once dubbed it, "the indispensable nation."