How secure are Pakistan's Nukes?

Considering this morning news about the assination of Pakistani opposition leader Benazir Bhutto we may want to ask, how secure are Pakistan's Nukes?

Before we can seek to answer the question about security let's look at Pakistan's Nuclear Weapons:

The Natural Resources Defense Council (NRDC) estimates that Pakistan has built 24-48 HEU-based nuclear warheads, and Carnegie reports that they have produced 585-800 kg of HEU, enough for 30-55 weapons. Pakistan's nuclear warheads are based on an implosion design that uses a solid core of highly enriched uranium and requires an estimated 15-20 kg of material per warhead. According to Carnegie, Pakistan has also produced a small but unknown quantity of weapons grade plutonium, which is sufficient for an estimated 3-5 nuclear weapons.

You can read the entire report at: Pakistan Nuclear Weapons

To read a report on Pakistan's Present Capabilities follow this link: Pakistan


Now how safe are these weapons now?

I found the following article at:
http://www.metafilter.com/67746/Securing-Pakistans-Nukes

Given this morning's news, I figured we could all do with a primer on the state of security regarding Pakistan's nuclear weapons. It's a very murky situation, but here's a collection of some of the best available data & analysis. I won't even try to summarize or characterize the various articles, I think any attempt I'd make would reduce their information past usefulness. So here you go, make of it what you will:

U.S. Secretly Aids Pakistan in Guarding Nuclear Arms (NYT),

Inside Pakistan's Drive To Guard Its A-Bombs (WSJ),

Pakistan Nuclear Security Questioned (WP),

The Stand-off (New Yorker),

The Times’s Three-Year Silence on Pakistan’s Nukes (CJR),

Securing Pakistan's Nukes (Danger Room),

Pak nukes already under US control (Stratfor Report)

& finally a Permissive Action Link Primer.