An Afghan security officer asks people to get out of the site of a blast in Kabul, Afghanistan, on Thursday. A suicide car bomber detonated his vehicle outside the Indian Embassy, killing 17 people. The Afghan Foreign Ministry hinted at Pakistani involvement — a charge Pakistan denied.

AP / Musadeq Sadeq

WASHINGTON — Sen. Jack Reed has voiced significant concerns not only about the military command’s request for thousands of additional troops to fight a broad counterinsurgency in Afghanistan, but also about the leading alternative: Vice President Joe Biden’s call for a scaled-back fight that stresses special forces and aerial-drone attacks on al-Qaida terrorists in the Pakistan borderlands.

The Rhode Island Democrat, a former Army officer who is a key congressional adviser to the White House on military issues, said in an interview Thursday that he is still trying to “ask the hard questions and look for flaws” in the competing proposals under consideration by President Obama and is not yet ready to endorse or reject either one — or elements of both that might prove useful.

As Reed discussed Gen. Stanley McChrystal’s request for up to 40,000 more troops in Afghanistan, Mr. Obama was reported to be inclined to send only as many more as needed to keep al-Qaida at bay, and to be prepared to accept some Taliban involvement in Afghanistan’s political future.

Reed, who returned from his eighth wartime visit to Afghanistan last month, was an early advocate of overtures to elements of the Taliban that might be willing to bargain for a role in a stable Afghanistan. Reed has likened that prospect to the successful recruitment of Sunni rebel groups in western Iraq to side with the U.S. and the fledgling Iraqi government against al-Qaida. These “Sons of Iraq” were an important adjunct to the U.S. troop “surge” of 2007, in a counterinsurgency strategy that dramatically reduced violence and paved the way for American withdrawal.

While Reed was noncommittal on the proposals by McChrystal, Mr. Obama’s new commander in Afghanistan, and by Biden, he appeared to be searching for a middle ground.

For example, Reed stressed that he supports adding several thousand troops to the current U.S. force of 68,000 for one limited purpose: accelerated training of Afghan military and police forces.

Reed also said he wants an unspecified number of added troops who will act as “enablers” to Afghan forces — engineers, logisticians, transportation experts and the like. Nor did he rule out the possibility that some number — again unspecified — of new combat troops should be sent to Afghanistan.

Reed also cautioned against viewing the McChrystal “counterinsurgency” and the Biden “counterterrorist” approaches as either/or propositions. “Pure counterterrorism” might involve outright troop reductions in Afghanistan, he said; no one in the administration proposes that.

Quoting a “senior administration official,” the Associated Press reported Thursday that while Mr. Obama is still at least two weeks away from a decision, the emerging thinking suggests that he would be very unlikely to favor a large military increase of the kind being advocated by McChrystal. At the same time, the developing strategy would “not tolerate” the return of the Taliban to power, the AP quoted the official as saying.

The sharpened focus by Mr. Obama’s team on fighting al-Qaida above all other goals, while downgrading the emphasis on the Taliban, comes in the midst of an intensely debated administration review of the increasingly unpopular eight-year-old war.

On the issue of popular opinion, Reed said, “anything we do has to be sustainable” by the support of the American people. But Reed said the proper course of action is “to reach a substantive judgment” about what is needed to protect this nation’s interests in Afghanistan. “Then you make the arguments” to the public, Reed said, noting pointedly that the 2003 invasion of Iraq enjoyed broad popular support.

On the looming policy decision, Reed underlined Mr. Obama’s dilemma by raising concerns about both the McChrystal and the Biden proposals.

Reed expressed concern that McChrystal may have made two shaky assumptions that could undermine the plan he has presented to the president. That plan, Reed explained, is based on classic counterinsurgency doctrine that stresses “clearing” population centers of insurgents and “holding” the areas secure for the citizenry, followed by the “building” phase of generating stability through government services, better living conditions and popular support.

Reed said the first potentially flawed assumption in McChrystal’s plan is that the U.S. government is prepared to augment a major troop increase with enough civilian personnel to undertake the many public-works and government-building chores to generate the popular support vital to a counterinsurgency that will succeed in the long run.

Secondly, Reed questioned whether the U.S. can assume a sufficient level of cooperation from Afghanistan’s corruption-plagued leadership.

Even with many thousands more troops, Reed said, the counterinsurgency strategy cannot succeed without extensive support on the long-term “build” phase from a U.S. corps of civilian personnel and from the Afghan government.

At the same time, Reed expressed worries about Biden’s proposal for scaling back the U.S. mission to a counterterrorism struggle that would concern itself less with defeating Afghanistan’s Taliban rebels than with routing the al-Qaida terrorist network in havens on both sides of the Pakistan border.

If the U.S., its NATO allies and the Afghan government forces cede large portions of the country to Taliban control, Reed said, there is a high probability that al-Qaida forces would again find safe havens in such territories.

Reed also said it is possible that a scaled-back counterterrorism mission, relying heavily on special forces and aerial drone attacks, might gradually lead the vital network of intelligence sources to dry up — a big worry for those who depend on intelligence to plan attacks on al-Qaida.Forces in Afghanistan

•The United States currently has about 65,000 troops in Afghanistan. Approximately 31,000 of those are serving with NATO and 34,000 are under U.S. command. In addition, NATO countries have provided roughly an additional 30,000 troops.

 As of Thursday, at least 792 members of the U.S. military had died in Afghanistan, Pakistan and Uzbekistan as a result of the U.S. invasion of Afghanistan in late 2001, according to figures provided by the Defense Department to the Associated Press.

jmulligan@belo-dc.com