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Editor's note: Aaron David Miller is a vice president and distinguished scholar at the Woodrow Wilson International Center for Scholars and was a Middle East negotiator in Democratic and Republican administrations. Follow him on Twitter.

(CNN) -- Presidents often draw red lines to contain the actions of adversaries, but no red lines are more important than the ones the president sets to contain himself.

In the Middle East, President Obama has drawn three: to limit the U.S. role in the Syrian civil war, to avoid risky concessions to the mullahs on the Iranian nuclear issue, and to avoid going to war with Israel on the peace process.

This play-it-safe strategy annoys and alarms Republicans, foreign policy gurus and even Bill Clinton.

But it's perfect for a second term president whose real priorities lie at home and who is facing extremely hard choices abroad. Indeed, if the president has any strategy it's to avoid as much risk as possible and manage the U.S. role in a muddled Middle East as best he can.

Governing is about choosing, and Barack Obama has made his choices.

The once transformative president with the Nobel Peace Prize acted as if he thought he could change the world, at least in the Middle East.

Then reality intruded. Obama was ready enough to take risks in fighting terror and on national security issues. But he has grown increasingly risk-averse when it came to the truly complex challenges: Iran, Israel, and of course, Syria.

Here the sheer complexity and difficulty of the issues and his fear of failure has tempered the president's enthusiasm for serious engagement. The political risks of fighting with the Israelis on settlements or appeasing the Iranian regime on the nuclear issue took care of the rest.

Nor was the public pushing for big engagement abroad. If anything, Americans wanted an end to the roller-coaster foreign policy of the Bush 43 years and a focus on their economic travails. The people and their president were only too happy with a steady, and generally competent, foreign policy defined neither by spectacular successes nor spectacular failures.

So on Iran, Syria, and the Israeli-Palestinian conflict, Obama discovered the Goldilocks principle. And that meant identifying an approach that was neither too hot nor too cold; neither too bold, nor cautious -- a careful middle ground designed not so much to tackle foreign policy challenges as to avoid them.

On Syria, the president's latest move to offer lethal assistance to carefully vetted rebel groups is the least encumbering move he could have made. He's not going to unilaterally raise the stakes any time soon unless forced to by the Syrians, with, for example, a massive use of chemical weapons.

Indeed, his move to arm the rebels is designed neither to force the regime to the table nor to defeat it. There's just not enough military juice for that. The fact is Obama can slow walk this arm-and-train exercise for months.

On Iran, the election of the pragmatic cleric Hassan Rouhani may well open up new possibilities on the diplomatic front. But the president will be reluctant to test them if it means having to offer concessions on the issue of enrichment that go beyond what the P 5 plus 1 group negotiating with Iran (United States, Britain, China, Russia, France and Germany) had offered, or making risky promises on sanctions relief.

The Iranian nuclear issue, like the Syrian crisis, will offer up no quick solutions or easy choices. Iran's role in supporting the regime of President Bashar al-Assad and the militarizing of the U.S. role there will only make the president's choices more difficult, reduce his flexibility and increase the need to stand tall and not show weakness. Rouhani or no Rouhani, the mistrust of the mullahs by the White House and Congress runs deep.

On the Israeli-Palestinian issue, the president is likely to continue an approach of cautious management, not risky initiatives to resolve a conflict not suitable for a timely settlement.

Secretary of State John Kerry may yet succeed in getting the Israelis and the Palestinians to the negotiating table.

But how to keep them there is another matter, let alone how to reach an agreement on the toughest issues like Jerusalem and refugees. If Kerry hasn't been told this directly, he's likely figured it out on his own: Don't create tensions with Netanyahu. In short, don't reset the reset that flowed from the president's reconciliation trip to Israel earlier this year.

Events beyond his control of course could cause Obama to violate his own red lines. to turn pink. He could be drawn deeper into Syria or into unanticipated diplomacy or conflict with Iran. But Obama's risk aversion runs pretty deep and has a powerful logic of its own.

Syria, Iran and the Israeli-Palestinian issue are long dramas, carry domestic political risks, and have very uncertain outcomes without clear upsides, particularly for a second-term president who believes his legacy rests on the domestic side.

This president will go to great lengths to avoid risky initiatives on both war and peace. Instead he'd prefer a process to manage these challenges as best he can.

In the end, he'd be quite happy to pass these headaches along to his successor. And it would be an exquisite irony if that person turned out to be his old rival and more recent friend -- his loyal Secretary of State Hillary Clinton, who never really got a chance to deal with any of these challenges the first time around.

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The opinions expressed in this commentary are solely those of Aaron Miller.