Sen. John Kerry, left, coordinated his discussions with President Hamid Karzai with Washington, sources say.

Elise Labott
CNN State Department Producer

Fresh from a trip to Afghanistan, Senator John Kerry warned against a narrowing of the US mission there, but suggested a plan by the commanding US general in the country is overly ambitious.

In a speech to the Council on Foreign Relations the chairman of the Senate Foreign Relations Committee warned a major US troop pullout could trigger a civil war could between the Taliban and the Afghan goverment and destabilize neighboring Pakistan.

He rejected the idea of a small-scale counter-terror campaign advocated by Vice President Joseph Biden, saying it was no substitute for the wider ongoing military campaign

But he also would not endorse a major troop increase as proposed by General Stanley McChrystal, saying the general's request for 40,000 troops "reaches too far too fast."

Kerry just returned from Afghanistan and Pakistan, where he played a key role in persuading Afghan President Hamid Karzai to accept a runoff election after his election victory was found to be the result of widespread voter fraud.

By making the case for a middle-ground option: a limited counterinsurgency strategy with the potential for deploying more troops over time, Kerry treaded between fellow Democrats who oppose a greater stake in Afghanistan and Republicans who caution the Obama administraiton risks losing the war, and putting soldiers at risk, by rejecting McChrystal's request.

He also gave cover to President Barack Obama as he considers a greater troop committment to the eight-year war there.

Kerry said three conditions must be met before President Obama decides to deploy more troops to the region: assurances that there are enough reliable Afghan forces to partner with US troops and eventually assume responsbility for security, support from the country's local and tribal leaders and a civilian surge to match the military increase.

"Under the right circumstances, if we can be confident that military efforts can be sustained and built upon, then I would support the President should he decide to send some additional troops to regain the initiative," Kerry told the Council of Foreign Relations. "Absent an urgent strategic imperative, we need a valid assessment by the President and other appropriate civilian authorities – not just the military - that those three conditions will be met before we consider sending more soldiers and Marines to clear new areas."

Kerry's current assessment of the Afghan's ability to partner with the US was grim, saying the US does not have the ""critical guarantees of governance and development capacity."

"The bottom line is that deploying additional troops won't result in sustainable gains if the Afghan security, civilian and governance capacity isn't there. And right now, as our generals will tell you, in many places, too many places, it isn't," he said. "I also have serious concerns about the ability to produce effective Afghan forces to partner with, so we can ensure that when our troops make heroic sacrifices, the benefits to the Afghans are clear and sustainable."

Success, he said, will be when the US can ""empower and transfer responsibility to Afghans as rapidly as possible and achieve a sufficient level of stability to ensure that we can leave behind an Afghanistan that is not controlled by al Qaeda or the Taliban."

"Achieving our goals does not require us to build a flawless democracy, defeat the Taliban in every corner of the country, or create a modern economy-what we're talking about is "good-enough" governance, basic sustainable economic development, and Afghan security forces capable enough that we can drawdown our forces," he said

Kerry said increased development efforts could also help with counterinsurgency operations by winning the hearts and minds of the Afghan people, a strategy advocated by Secretary of State Hillary Clinton. On Monday the State Department said it was on track to meet the goal of tripling its civilian staff in Afgahnistan, from 320 in January to 974 by early 2010. Kerry echoed comments made in the past by Clinton, saying it was important for civilian workers to be protected with the proper number of troops.

He also emphasized the importance of instensifying support and improve cooperatioin with Pakistan, saying, "given the balance of our strategic interests, it should give serious pause to military and civilian strategists alike that the current balance of our expenditure between Afghanistan, where there is virtually no Al Qaeda, and Pakistan, where there is, tallies thirty-to-one."

Blasting the Bush administration for its "gross mishandling" of the war in Afghanistan, Kerry said the Obama administration was left with "no great options for its handling today."

"One American officer captured well our lack of a strategy when he said, 'We haven't been fighting in Afghanistan for eight years. We've been fighting in Afghanistan for one year eight times in a row.' That is our inheritance," Kerry said.

Still, he said, "it was not a mistake to go in" after 9/11 to attempt to root al-Qaeda from the country.

""We now have to choose a smart way forward so that no one is ever compelled to ask whether we've made a mistake in staying," he said.