British historian Paul Johnson shares with Forbes readers his unflattering assessment of the 44th president’s response to the nation’s largest foreign policy challenge. No, I’m not describing climate change.

Only two entities have had much success in standing up to ISIS. One is the rump of the old Syrian state, controlled by the Assad family, which has access to modern weapons via its backer, Russian President Vladimir Putin. The other is the Kurdish fighters who operate along the Turkish, Syrian and Iraqi borders and who are inspired by a genuine nationalism that gives this group a self-sustaining drive akin to ISIS’ own. The Kurds, however, want to set up their own state, to which Turkey is implacably opposed.

Organizing an effective anti-ISIS coalition will therefore require a coalition leader of worldwide resources–military and financial–stature, authority and diplomatic skill. Only the U.S. has the ability to take this on in the way such a role was originally conceived by Dwight Eisenhower, both as military commander and as President, and later by some of his successors, notably Presidents Ronald Reagan and George W. Bush. Unfortunately, President Obama completely fails to measure up to the character requirements demanded by his natural position as world leader.

It’s astonishing that Vladimir Putin has been able to play a major role in the Middle East, upstaging Obama completely. Because, with the exception of nuclear firepower, Russia isn’t in the same league as the U.S. For example, it has only 230,000 active army personnel, compared with the U.S. Army’s 539,450. Its navy personnel total 130,000; the U.S. Navy, 326,800. And its air force is made up of a mere 148,000 people, compared with the U.S.’ 334,550. Russia spends only $70 billion a year on defense, whereas the U.S. pays out nearly ten times that amount–$581 billion.

These figures from the International Institute for Strategic Studies’ annual report underscore how little the U.S. has to show for its expenditures. And why is this? Because Barack Obama is one of the weakest chief executives in U.S. history, cowering in the Oval Office before the magnitude of his nation’s problems and his inability to face them. The result is that ISIS has been allowed to appear to be a threat of incomparable magnitude–one beyond the physical resources of the West.

This is, of course, nonsense, but that needs to be demonstrated by one of the West’s leaders.