(For more on Afghanistan, click on [nAFPAK])
* Obama promises to announce his decision "shortly"
* Television address expected next Tuesday evening
* Military chiefs favor 30,000-plus troop increase (Updates with quotes, background)
By Jeff Mason and Adam Entous
WASHINGTON, Nov 24 (Reuters) - President Barack Obama said on Tuesday he will announce his decision soon to send more U.S. troops to Afghanistan in an effort to "finish the job" of an unpopular and costly eight-year war.
Obama, at a joint news conference with Indian Prime Minister Manmohan Singh, spoke a day after the final meeting of his war council as he concludes a three-month strategic review process that Republican critics have called dithering.
Influential voices in Obama's national security cabinet, including Defense Secretary Robert Gates and military chiefs, favor a U.S. troop increase of 30,000-plus, officials said. The final number could reach 35,000 once U.S. trainers are factored in, but estimates on the number of trainers vary widely.
Obama would not be drawn out on specifics but said he would have an announcement on how to proceed after this week's Thanksgiving holiday. He is expected to give a television address next Tuesday evening.
"After eight years, some of those years in which we did not have, I think, either the resources or the strategy to get the job done, it is my intention to finish the job," Obama said.
"I will be making an announcement to the American people about how we intend to move forward. I will be doing so shortly," he said.
There are about 110,000 foreign troops, including 68,000 U.S. soldiers, in Afghanistan fighting the Taliban. War spending in Afghanistan has more than doubled over the last year and reached $6.7 billion in June alone.
Obama has been reviewing war strategy since Army General Stanley McChrystal, the top U.S. commander in Afghanistan, said in a report that conditions were deteriorating and 40,000 additional troops were needed to quell the insurgency.
The president stressed that civilian and diplomatic efforts would be key to his strategy and said he would discuss the responsibilities of other nations and Afghanistan itself when laying it out.
"One of the things I'm going to be discussing is the obligations of our international partners," he said.
"The Afghan people ultimately are going to have to provide for their own security, and so we'll be discussing that process whereby Afghan security forces are properly trained and equipped to do the job," he said.
ROLL-OUT, AMERICANS DIVIDED
Gates, McChrystal, Joint Chiefs of Staff Chairman Admiral Mike Mullen and U.S. Ambassador to Afghanistan Karl Eikenberry will appear before congressional committees in the days after Obama's announcement to testify about the troop buildup.
Obama faces conflicting pressures on Afghanistan.
While military advisers favor a bigger increase, other top White House advisers have been pushing behind the scenes to keep the total number closer to the 20,000-range with a sharper focus on training Afghan security forces, officials said.
Vice President Joe Biden has been a leading skeptic about increasing troops and Eikenberry, who commanded U.S. troops in Afghanistan in 2006 and 2007, has expressed deep concern about sending more troops until government corruption there abates.
Americans are divided on the issue.
Republicans in Congress insist more troops are needed to roll back a Taliban resurgence, while the president's fellow Democrats in general would like to see the United States find a way out of Afghanistan.[ID:nN24311026]
"I feel very confident that when the American people hear a clear rationale for what we're doing there and how we intend to achieve our goals, that they will be supportive," Obama said.
The president signaled that the destruction of al Qaeda "and its extremist allies" would remain the focus of his new strategy. Some in his administration, including Biden, have questioned, however, the need to send more troops to fight the militant group when it is believed to have fewer than 100 fighters in Afghanistan.
Obama said it was in the United States' strategic and national security interests to dismantle al Qaeda networks in the region, echoing similar comments he made when he unveiled his first Afghan strategy in March.
The Pentagon envisages Obama's troop build-up to unfold gradually, with the deployment of approximately one brigade, plus so-called "enablers" or support troops, per quarter starting by spring 2010, military officials said. [ID:nN24307797]
That means the buildup could drag well into 2011, depending on the number and types of brigades sent.
Afghanistan's poor infrastructure will make it difficult to field and equip more than one brigade plus enablers every three months, the officials said. Enablers include transport support, mine detection and clearance units and medical staff. (Additional reporting by Steve Holland and Ross Colvin; editing by Eric Beech) (For more Reuters coverage of Afghanistan and Pakistan, see: here)
((firstname.lastname@example.org; +1 202 898 8392; Reuters Messaging: email@example.com))))