Climbers have tradionally used routes that cross the border to get into famous peaks like Mt. Redoubt, Bear Mtn, Castle Peak and the Cathedral Group. The National Park Service has even maintained a sign-in register just past the border in Depot Creek as it's is part of the NCNP.
Obviusly none of these routes are particularly convient for smuggling compared to Zero Avenue (a long road in Canadian approximately 5' north of the official borderline) or some backroad near Sumas, so I find it hard to imagine that climbers will be targeted, but.............
Watch Out! 69 law enforcement officers, 1 airplane and two "sensor-equiped" helicopters (at least one is black!) are moving to Bellingham where they will vigilantly be searching for illegal imigrants, BC-bud, the always ominous WMD and eating plenty of donuts. Better find a new way to get that backpackable-nuke across the border folks.
B'ham Border Protection Office