Washington - The largest military offensive of the eight-year war in Afghanistan, launched this weekend in southwestern Helmand province, is a crucial test for President Barack Obama's strategy of more troops, more civilians and more money.

In an acknowledgment of past mistakes, administration officials have emphasized that for the first time, U.S. and NATO forces are outnumbered by thousands of Afghan soldiers fighting alongside them. Unlike previous offensives, in which territory won from insurgents was later abandoned, the troops plan to clear the Taliban stronghold of Marja and hold it for as long as it takes to install a functioning local security system and government.

Large numbers of Afghan and international civilians have been marshaled to move into the district once the fighting is over, and development projects are funded and ready for implementation.

"What's important about this operation is that it is the first major operation in which we will demonstrate, I think successfully, that the new elements of the strategy - which combine not only security operations but economic reform and good governance at the local and regional level with a much more visible presence of Afghan forces - will take place," Obama's national security adviser, retired Marine Gen. James Jones, said on "Fox News Sunday."

White House officials said Obama was closely monitoring the situation, with regular updates and briefings from Jones and Defense Secretary Robert Gates. The officials said Obama spoke with Gen. Stanley McChrystal, the top U.S. and NATO commander in Afghanistan, on Sunday morning, but declined to provide details of the conversation.

Republican leaders have often criticized the administration's national security policy, but they voiced strong approval of the operation. Sen. Jon Kyl, R-Ariz.,, the Republican whip, said on CNN that he had recently returned from Afghanistan, and that "the situation does seem to be definitely improving. There's a very good plan."

McChrystal, who supplied the initial framework for the strategy Obama announced in December, has a lot riding on the offensive. The first conducted since Obama authorized deployment of 30,000 additional troops, it is being waged under new guidelines McChrystal put in place for forging better ties with the local Afghan population.

U.S. troops have been told to end the "night raids," in which they barged into Afghan homes in search of insurgents, and to send in Afghan forces first. Meetings were held with tribal leaders from the Marja region before the well-advertised offensive began, and news reports from the battlefield indicate that commanders are wary of disrupting the lives of civilians.

Although U.S. forces have already called in several airstrikes against dug-in Taliban concentrations, the operation favors ground movements in an attempt to avoid civilian casualties. McChrystal was quick to issue a public apology to Afghan President Hamid Karzai Sunday after two U.S. artillery rockets missed their target by a nearly a fifth of a mile, killing 12 civilians.

In a statement issued by the International Security Assistance Force (ISAF), the multinational coalition McChrystal leads, he said use of the rocket system was being suspended pending a review of the incident.

The administration also hopes that a decisive blow against the Taliban on its home turf will further efforts to persuade low-level fighters to change sides. NATO commanders and Afghan leaders have been formulating a plan to use jobs and other incentives to persuade insurgents to abandon the Taliban.

"The hope is that we'll get further cooperation from the people in the region," Vice President Joe Biden said on NBC's "Meet the Press," particularly "the Pashtun tribes who will see more accommodation coming out of the Taliban, most of whom are Pashtun, realizing that they cannot realize their expectations through intimidation and force."

Helmand is the site of the most intense concentration of Taliban fighters in the country. Coalition forces, primarily British, have been fighting there for years.

But they lacked the manpower to hold territory, leaving villagers reluctant to support them out of fear of Taliban retribution when they inevitably withdrew. Afghan troops expected to accompany Marines who began moving south along the Helmand River last spring showed up in the hundreds, rather than the anticipated thousands.

To the extent the Marines and the British have expanded their reach in recent months, it has been largely due to the Taliban's withdrawal and regrouping in the heavily fortified area of Marja, a region crisscrossed by canals and minefields.

"Instead of clearing one area and leaving, as we frequently did in the past," Jones said on CNN, "our plans call for clearing the area, holding the area, and then providing some building for the people there, better security, better economic opportunity, better governance, more of an Afghan face."

A "successfully demonstrated and executed operation" in Marja, he said, "is going to make a big change in not only the southern part of Afghanistan, but will send shock waves through the rest of the country that there is a new direction, there's a new commitment."