His Cabinet nominees offer important clues.
President Obama's choices for his national security team could help him consolidate some of the signature policies he developed in his first term, from his strategy for ending the war in Afghanistan to his dependence on drone strikes in the fight against al-Qaida.
They will raise important questions about others, including his stated determination to prevent Iran's acquisition of a nuclear weapon by military means if necessary.
Consequently, the confirmation hearings of Chuck Hagel for the Defense Department, John Brennan for CIA director and John F. Kerry for the State Department could provide a needed debate on the direction of U.S. national security policy - provided that senators can avoid distractions.
Chief among the distractions would be charges that Mr. Hagel, a former Republican senator from Nebraska, is hostile to Israel or even anti-Semitic. There is no serious evidence to support either allegation.
Certainly Mr. Hagel's views about the Middle East have often been outside the mainstream - except on the Iraq war, where he was anything but the savant that the White House describes. (Having voted to authorize the invasion in 2002, Hagel denounced the 2007 surge as "the biggest foreign policy blunder since Vietnam.")
But there's no reason to believe Hagel would not, as Pentagon chief, continue the close military cooperation with Israel maintained by predecessors Leon Panetta and Robert Gates - who were also publicly critical of Israeli policies at times.
The real issues raised by Hagel's nomination are his past support for a quick-as-possible withdrawal from Afghanistan, a further downsizing of what he described as a "bloated" Pentagon and his resistance to foreign interventions.
To a large degree, these views are shared by Mr. Kerry, a fellow Vietnam veteran, and coincide with Obama's plans for his second term. So the Senate ought to explore and debate their potential benefits and risks.
Can defense spending sustain large cuts beyond the more than a half-trillion dollars Mr. Obama sliced during his first term? Can Afghanistan avoid another civil war if U.S. troops are rapidly withdrawn in favor of a minimal stay-behind force - or none at all? Is it wise for the United States to remain passive as the civil war in Syria intensifies and threatens to spread to its neighbors?
Then there is the challenge of Iran: In contrast to Obama, Hagel has suggested that containment of an Iranian nuclear weapon could be an acceptable policy, and he has opposed both military action and unilateral U.S. sanctions. In Tehran, his appointment might be taken as evidence that the Obama administration would not act if Iran refused to brake its steps toward a bomb.
But is it? Or would Hagel support the president's choice of military measures if negotiations fail? The question is far from academic: Israel's government believes that Iran's pursuit of a nuclear capacity could reach the point of no return by the middle of this year, and Israel may strike on its own if it concludes that U.S. intervention cannot be relied upon.
We argued that Hagel was not the best choice for defense secretary because of his views on the budget and Iran, and because superior candidates were available. We've also made the case that the administration's current strategy of countering al-Qaida in Pakistan, Yemen and Somalia with drone attacks is unsustainable. The architect of that policy is Brennan, who as the White House's counterterrorism czar has overseen and personally approved kill lists for drones.
To his credit, Brennan has reportedly resisted efforts by the Pentagon to expand targeting lists in Yemen and has insisted that attacks center on al-Qaeda activists who pose a direct threat to the United States. The strikes are certainly legal under U.S. and international law, yet the secrecy with which the target lists are drawn up, and the strikes' frequent execution by the CIA rather than military forces, are problematic - as is the political backlash they have caused in Pakistan.
Brennan's prospective move to the CIA offers Congress the opportunity to reconsider and adjust the drone program. A central question is whether drone strikes and other paramilitary action should continue to be a CIA responsibility: As acts of war, they would best be carried out by military forces and subjected to the review and disclosure of other military operations.
As important, the process for developing targets should be brought out into the open and authorized by Congress, just like the rules for military detention and interrogation. Brennan should be pressed to explain the current system and asked why the CIA under his tenure should not be refocused on the job of intelligence collection.
A larger question is whether Obama's combination of troop withdrawals, non-interventionism and the heavy use of drones will protect U.S. interests in the roiling Middle East. Brennan himself has said that drone attacks alone will not end the threat of al-Qaida; policies that bolster fragile governments like that of Yemen, and prevent the disintegration of others - think Iraq or Pakistan - are also needed. While serving in the Senate, Kerry has been a proponent of such policies, but in the last year Mr. Obama has appeared to back away from them in favor of "nation-building here at home."
Presidents are entitled to have their Cabinet picks confirmed if they are qualified, and nothing disqualifying has emerged about these three. But their confirmation hearings offer an opportunity for the Senate to weigh Obama's strategy.
It's certainly tempting to think that the United States can withdraw all but a few thousand troops from Afghanistan, stand on the sidelines in Syria, contain Iran with U.N.-approved sanctions, pivot U.S. resources to Asia and ward off any lingering terrorist menace with drones. Whether that is a realistic strategy for Obama's second term ought to be the overriding subject of the upcoming hearings.