You can see why a president might have a hard time understanding the world. He leads America out of two costly wars and resists the temptation to get the country involved in new military interventions - but at home and on the international stage he is met with bitter criticism. Domestic approval ratings are in the dumps, and it doesn't look good for his international credibility either.

Two-and-a-half years before the end of his presidency, Obama is increasingly going on the defensive. Not only American troops are in retreat - their commander in chief is as well.

With his speech to the cadets at United States Military Academy at West Point, he sought to change tack and awaken new confidence and trust among his allies. Alas, he did not achieve this. His speech was not a slam-dunk - it was neither emotional nor concrete enough. Many questions remain open with regard to his future foreign and security policy. The visibly tense president spent more time looking back than ahead.

As has been the case all too often at such moments, Obama acted out of self-defense. True, he did - as promised - end the war in Iraq; and by the end of his term, no noteworthy number of troops will remain stationed in Afghanistan. But at what price? Iraq is sinking into violence and chaos, and Afghanistan is threatened by the same fate.

What's also true is that the world is rapidly changing, and responses to crises and conflicts have become more complicated. With the statement "America must always lead on the world stage," Obama continued to insist that the United States - despite retreating troops and self-imposed restraint - continues to play a decisive role in the world. But America under Obama is no longer the indispensible nation that it was when former Secretary of State Madeleine Albright gave meaning to these words.

The country, which remains a superpower, has not yet found its role in this changed world. This time around, one could sense in Obama more tentativeness and uncertainty. That's not leadership.

Obama made it clear that the United States will only militarily intervene in emergencies - and even then, preferably together with allies and international organizations. Is this the new-old Obama doctrine? Unfortunately, he neglected to specify what that means concretely for conflicts like in Syria or Ukraine, and what effects this could have on relations with Russia and China.

The doubts remain. This explains the call on Obama, repeated like a mantra, to finally follow his words with actions. This call will continue to be made of the president, from Ukraine to Syria, from allies in the Arab World to NATO member states on the eastern periphery of the alliance.

But Obama would like to return those messages to their senders. It seems that others should be taking up responsibility and resolving the crises at their doorsteps. Obama's rejection of American authority and his acknowledgement of multilateral action cannot be understood in any other way. The new coalition for action against terror looks to be a rescue party for leftover US engagements - even if it is backed by billions of dollars.

Europe, as well, should listen to this message. The times of Americans delivering free security are over. The Ukraine crisis is a taste of what's to come.