Q+A-What is Pakistan doing about the Taliban threat?

ISLAMABAD, May 5 (Reuters) - Pakistani authorities urged people on Tuesday in the Swat Valley's main town to leave their homes for safer places as security forces could soon launch an offensive against Taliban militants there.

A February peace pact aimed at ending Taliban violence in the Swat valley northwest of the capital has all but collapsed as nuclear-armed Pakistan comes under U.S. pressure to get tough with the militants rather than appease them.

President Asif Ali Zardari, widower of former prime minister Benazir Bhutto, is due to meet U.S. President Barack Obama and Afghan President Hamid Karzai in Washington on Wednesday for talks on the growing militant threat in the region.

Here are some questions and answers about the issues in Swat and the surrounding region.

WHAT IS AT STAKE?

From Swat the militants had moved into neighbouring Buner area, just 100 km (60 miles) northwest of Islamabad. Failure to stem the Taliban's creeping advance from enclaves in ethnic Pashtun tribal areas on the Afghan border sparked worry among both Pakistanis and Western allies that militants were close to the gateways to Islamabad.

A military spokesman said a few hundred militants in the mountains never posed a real threat to the capital. But some security analysts said the guerrillas could have used Buner as a jumping-off point to strike at Tarbela, a dam that provides water and electricity to much of the country. The militants had also moved closer to a road running north to China.

Before the military offensive in Buner, Western allies, who need Pakistani help to defeat al Qaeda and stabilise Afghanistan, worried the government seemed too willing to appease militants.

While Swat, about 130 km (80 miles) northwest of Islamabad, is not on the Afghan border, Western countries with troops in Afghanistan fear the area could become a bastion for militants fighting in both Afghanistan and Pakistan.

Obama said last week he was confident about the security of Pakistan's nuclear arsenal but the New York Times reported growing U.S. concern militants might try to snatch a weapon in transit or insert sympathisers into laboratories or fuel-production facilities.

ARE THE MILITARY ACTIONS A RESPONSE TO U.S. PRESSURE?

The military moves in Buner and subsequent actions in Swat itself came on the heels of a visit to Islamabad by Admiral Mike Mullen, the chairman of the U.S. Joint Chiefs of Staff, who may have played a role in persuading the weak civilian-led government to act, and before the talks in Washington where Zardari is likely to press for more U.S. military and economic aid.

Washington is considering rushing hundreds of millions of dollars in emergency aid, the U.S. Senate's second-ranking Republican, Jon Kyl of Arizona, told reporters.

U.S. officials have applauded the military action in Buner and urged the Pakistan military to keep the Taliban on the run.

Army chief General Ashfaq Kayani has said the military halted its operations in Swat early last year in order to give politicians space to negotiate, but added the army would not allow militants to impose their will on the country.

Kayani has to counter a general perception the army, whose main focus has been a perceived threat from old rival India, is demoralised and reluctant to fight Pakistani Muslims in Swat, although security forces defeated the Taliban in the Bajaur tribal area on the Afghan border in March.

WHAT WAS BEHIND THE SWAT PEACE DEAL?

Many people from Swat were caught up in the siege of Islamabad's Red Mosque in July 2007, which commandos stormed to put down a militant movement, resulting in at least 100 deaths.

Violence flared in Swat later that year, and while military operations pushed the Taliban back, they regrouped as soon as the army relented to allow politicians space to negotiate a peace.

The North West Frontier Province government led by the Awami National Party (ANP), an ethnic Pashtun party allied to Zardari, struck a deal with a radical cleric in February to impose sharia law in the hope of ending violence.

Zardari sanctioned the imposition of Islamic law in Malakand after parliament passed a resolution last month. Days later, Taliban fighters entered Buner and nearby Shangla district, raising alarm at home and in the West. link..