US Secretary of State has expressed her deep concerns over the security of Pakistan's nuclear arsenals amid escalating Taliban insurgency.
Hillary Clinton in an interview with Fox News on Sunday in Baghdad, said the US was worried about the 'unthinkable' in Pakistan -- that the Taliban and al-Qaeda could topple the government, giving them "the keys to nuclear arsenal."
Her comments come amid reports that Taliban militants are planning to infiltrate into the capital and its adjoining areas.
She also emphasized that Washington was pushing hard for Pakistani factions to come together around a strategy to take their country back from the extremist militants.
Last week, Clinton had accused Islamabad of abdicating to the insurgents and asked the Pakistanis around the world to speak out against their government's policy of ceding land to the militants.
She had also emphasized that Pakistan posed a 'mortal threat' to world security by accepting Taliban's desire for autonomy in the Swat valley.
In addition, Pentagon Chief, Robert Gates, warned that the US would severe its relations with Pakistan unless Islamabad crushed the Taliban-led insurgency.
Last week, Taliban militants armed with heavy weapons reportedly took control of at least two districts near the capital of the nuclear-armed country.
Taliban's loose control over some districts near the capital has put Islamabad on red alert several times during the past weeks. The areas are located almost 100 km (60 miles) away from Islamabad.
The US invasion of Afghanistan in 2001 has prompted militants to cross the border into Pakistan, turning the restive tribal belt between the two neighbors into scenes of deadly violence.
Pakistan has dismissed US concerns, saying its armed forces have full control over the country's nuclear installations.