Your post #152 and #154 were an interesting read.
I think that much of the concern about the far northern reaches of Kashmir, is more a concern about a possible linkage (or sanctuary, support, etc.) with China via the Khunjerab (Karakoram) Pass. It has a drivable road that enters China at "only" 16,200 feet.
Back in January, we had a conversation (here with more in #12) with poster "rogue yam", who related his (harrowing) bus trip in 1987 from China to Pakistan via this very same pass.
However likely or unlikely, clandestine Chinese collaboration with al-Qa'ida and Osama bin Laden may seem, the possibility can't be ignored.
--Boot Hill
"However likely or unlikely, clandestine Chinese collaboration with al-Qa'ida and Osama bin Laden may seem, the possibility can't be ignored."
Agree this possibility can't be ignored - What are the borders like near China - Do the Chinese have a strong military presence there or are the borders pretty open? - I would expect many Muslims to be living on the Chinese side of the border as well - which would make one think UBL could have friends there - no?
There's at least one documented tie between Al Qaida and China. After Clinton's retaliatory strike in Sudan and Afghanistan, China either purchased or was trying to purchase unexploded TLAMs that Al Qaeda had found on the approaches to the target areas.
The following is derived from secondhand sources so take it with a grain of salt. The road crossings at the Chinese border are checkpointed, with a sizable military presence at each. Relationships with Western climbing expeditions are chilly but correct. Paperwork must be exactly in order, there is some searching of gear and trucks, with particular emphasis on what is being brought into China. Outgoing concerns seem to be much lower. This general situation has been reported at numerous points across the border areas in both Pakistan and Nepal. With many of these expeditions routinely used to bribing Nepalese and Pakistani Customs agents, in order to get them to overlook the import of beef, currency, quantity restrictions etc., it is noteworthy that I do not recall any attempt or even consideration of bribing the Chinese Border Guards at the checkpoints.
There is significant patrol activity, even at higher altitudes. Climbers looking to sneak across the border for a quick unlicensed summit are extremely careful not to make contact with patrols or with traveling locals. The assumption is that the locals will pass on sightings of foreigners to the Chinese troops.
The troops themselves seem to fit the description of "remote border garrisons", largely autonomous to local authority, somewhat contemptuous of the majority of border crossers, brought on by contacts largely limited to mountain locals.
While the conditions described do not seem conducive to smuggling, if it does take place the likely channels would be via small village officials on the Chinese side who had established contacts with the border guards, and with regular cross border trafficers. As for the porosity of the border, the climbers can and do make it across and back without interference, but they stick to remote passes, and use extreme caution. Many of these passes are at 19,000 feet or higher and the conditions can be fearsome.
Based on the general overview provided by the different accounts available, it seems that cross border terrorist operations would be more in the nature of temporary safe haven, with permanent presence on the Chinese side less likely. The Guards do not promote familiarity, and maintain living accomodations apart from local populations. Unlikely, but not impossible. If anyone would be likely to find cracks in the border, it would be Bin Laden.
Something else to consider when looking at trafficability in that region, is that a major feeder route into the Wakhan Corridor is the Panjshir Valley, but that the residents there would be significantly hostile to both the terrorists and the Taliban. There is a long period of conflict between the two, beginning during the Russian occupation. The inhabitants of the Panjshir, under Gen. Masood, (The Lion of the Panjshir) were in direct competition with the jihadists over funding from the US and Saudi Arabia, funnelled through the Pak ISI. After the fall of the communist government in Kabul, Masood was appointed secretary of defense in Kabul, weathering many attacks from the jihadist sympathizer Gulbuddin Hekmatyr, before being ousted by the Taliban. Finally, on 9/9/2001, Al Qaeda terrorists assassinated Masood, leaving his Northern Alliance troops behind to fight under the temporary command of Gen. Dostum, who was based at Mazar-i-Sharif.
There are other conduits through the valleys and over the passes, but I would strongly suggest that the main road running through the Panjshir woukd be an unfriendly or even hostile environment for radical proponents of Islam.