Despite a fierce U.S. military campaign aimed at paralyzing the Taliban in Afghanistan, insurgents have largely been able to absorb attacks and are playing a waiting game until July, when the U.S. troop drawdown is scheduled to begin, military and intelligence officials reportedly say.

While stepped-up airstrikes and special operations raids have damaged local Taliban cells, the attacks have not had a meaningful impact on the terror organization and have failed to put pressure on the group to seek peace, the officials reportedly said.

"The insurgency seems to be maintaining its resilience," a senior Defense official involved in assessments of the war told The Washington Post. The Taliban have consistently shown an ability to "reestablish and rejuvenate" within days of being hit by U.S. forces, the official continued.

Assessments made by the Central Intelligence Agency and Defense Intelligence Agency found that Taliban commanders killed or captured are often replaced within a matter of days, and in territories such as Kandahar where insurgents have been forced to flee temporarily, the groups are simply waiting for the opportunity to return, the Post reported.

U.S. officials said Taliban agents are intentionally holding back efforts until the start of President Obama's troop drawdown in July of next year. "The end is near," they tell one another, attributing the words to Taliban leader Mohammad Omar, the newspaper said.

The Obama administration plans a review of the war effort in December, which has triggered jockeying between U.S. military leaders looking to continue the troop surge and critics who argue the American role should be downsized.

Last week, top U.S. commander Gen. David Petraeus said progress against the insurgency was occurring "more rapidly than was anticipated," but acknowledged major hurdles lie ahead. 

Officials told the paper the main two insurgent groups -- the Taliban and Haqqani network -- have been able to bear the U.S. campaign primarily because they have access to sanctuaries in Pakistan.

Meanwhile, on Tuesday Iran acknowledged it has been sending funds to Afghanistan for years, but said the money was intended to aid reconstruction, not to buy influence in the office of Afghan President Hamid Karzai.

U.S. officials asserted the money flowing from Tehran was proof that Iran is playing a double game in Afghanistan -- wooing the government while helping Taliban insurgents fighting U.S. and NATO forces.

Karzai said Monday he receives millions of dollars in cash from Iran, adding that Washington gives him "bags of money" too because his office lacks funds.

In Washington, President Obama's press secretary, Robert Gibbs, denied that. "We're not in the big bags of cash business," he said Tuesday.

Earlier, State Department spokesman P.J. Crowley said some of the U.S. aid to Afghanistan is in cash.

Iran publicly opposed the U.S.-led offensive that toppled the Taliban after the Sept. 11, 2001, terrorist attacks in the United States, though its relations with the Taliban regime had been frosty.

The Associated Press contributed to this report.