Those who accuse Pakistan of being slow in addressing terrorism-related problems don't understand the situation the country is facing, Pakistani Ambassador Kamran Niaz said during a Wednesday visit to The Japan Times.

"Pakistan is a frontline state in the fight against terrorism more than any other state," Niaz said. "Critics say that Pakistan is not doing enough because the problems have not been eliminated so far. But the campaign may take maybe 10 years, maybe 15 years or maybe 20 years," Niaz said.

It isn't easy to counter al-Qaida and the Taliban in the north and elsewhere since they have established highly effective networks in the 20-plus years they've been there, he said.

The area where Osama Bin Laden is supposed to be stretches more than 1,000 km and it is impossible to pinpoint his location, the ambassador said.

Although 83,000 Pakistani troops are deployed along the 2,500-km Pakistani-Afghan border, people with terrorist intentions are crossing it both ways, he said. Only about 10,000 Afghan troops are manning the Afghan side of the border, he added.

Niaz also said that religious schools accused of nurturing extremism used to receive U.S. support to train and indoctrinate anti-Soviet fighters in the years when Afghanistan was under Soviet invasion. The U.S. supplied weapons while Saudi Arabia provided money.