WASHINGTON - The United States has acknowledged that Pakistani army offensive, now in its sixth week,  has succeeded in disrupting the militant groups in North Waziristan tribal region along the border with Afghanistan, The Los Angeles Times reported Thursday.

Citing Obama administration officials, the newspaper said that proof of the operation's success, will be whether groups such as the notorious Haqqani network are allowed to reconstitute themselves in North Waziristan or elsewhere and "again plot attacks against U.S.-led forces in neighbouring Afghanistan or elsewhere."

Previous Pakistani offensives in the tribal belt have either ignored groups like the Haqqanis — who are blamed for deadly attacks against U.S.-led forces in Afghanistan — or allowed them to return, LA Times said. U.S. military officials have been saying that top levels of Pakistan's security establishment back the Haqqanis as a proxy force to maintain influence in Afghanistan.

But with most U.S. forces withdrawing from Afghanistan at the end of the year, the U.S. military's ability to battle the Haqqani network is expected to diminish sharply. Obama administration officials have pressed Pakistan's military leaders in a series of meetings this month to ensure the group does not escape the current operation.

"We keep telling them they must go after all the terrorists and that they cannot cherry-pick," said a senior U.S. official who requested anonymity to discuss the sensitive talks. "We've been quite emphatic about that."

Tariq Fatemi, special assistant to Pakistani prime minister on foreign affairs, has said that the ongoing military operation was focused, objective-oriented, and most importantly directed at all militant and

extremists who are equally treated.

The special assistant told The Nation Pakistani military's well-planned operation would be far more successful and yield greater results should the US, NATO, ISAF and Afghan forces undertake similar operations on the other side of the border. "I was assured there was great merit  in my plea for a reciprocal action. "

The offensive, which began in mid-June and has resulted in the deaths of more than 500 militants and the seizure of large weapons caches and bomb-making factories, the dispatch said.

But some officials say that insurgents fled the area before the start of the offensive, which had been rumoured for several months.

U.S. officials say they have not received photographs or other visual evidence from Pakistan showing it has directly targeted the Haqqani network. In the end, the senior U.S. official said, "We end up having a good conversation but the bottom line is we have to be convinced there is no reconstituting of terrorist facilities and safe havens."

Some analysts say that Pakistan is taking action now because of a provision in the 2015 Pentagon budget that could withhold hundreds of millions of dollars in counter-terrorism funding unless Defence Secretary Chuck Hagel certifies that Pakistan has "significantly disrupted the safe haven and freedom of movement of the Haqqani network."

Now that they have begun such an operation, "the Pakistanis are making an argument in Washington that they should be given continued coalition support," C. Christine Fair, author of "Fighting to the End: The Pakistan Army's Way of War," said in a newspaper interview this week. Pakistan has received $28 billion in U.S. military and economic aid since 2002, and additional expenditures would be "outrageous," she said.