Historian Paul Johnson devotes his latest Forbes column to the Obama administration’s concerted effort to minimize the American role in world affairs.

UNDER PRESIDENT OBAMA the U.S. has effectively abdicated its role as world policeman. Using the failure of the war in Iraq as an excuse, America no longer even pretends to be the democratic superpower to whom the wretched of the world can look for help. This has left a moral and physical vacuum at the heart of the global community. And we’re learning the hard way that without a world policeman evil rulers flourish, and the people living under them have to put up with tyranny, however brutal and corrupt.

Take Syria. President Bashar al-Assad continues in power despite the fact that, according to the World Bank, “around half the population have been forced to leave their homes, with 7.6 million internally displaced, 3.8 million refugees, and more than 1.5 million nonrefugee migrants.” More than 200,000 are now believed to be dead.

This is one reason that sects such as ISIS have been able to establish themselves in Syria and in northern Iraq.

There are other, more flagrant examples of what happens when America’s presence weakens. Vladimir Putin, using the power of the Russian state, has amassed one of the largest fortunes in history and has enabled his circle of cronies, who keep him in power, to do the same. All while Russia’s national wealth has declined catastrophically. Industrial production is down nearly 5%, the price of foodstuffs has risen 20%, and 16% of Russia’s population now live below the poverty line.

None of this has prevented Putin from pursuing an aggressive military policy in eastern Europe: He has seized the Crimea; his troops, masquerading as Russian nationalists, occupy eastern Ukraine; and he threatens the Baltic states.