Surrendering U.S. turf : That's the impression given by new signs on some Bureau of Land Management land in southern Arizona. The signs -- which warn people to avoid the area south of Interstate 8 -- were installed after a local sheriff's deputy was reportedly shot by a Mexican drug trafficker in late April. "We have not closed BLM lands," says the BLM's Dennis Godfrey, but "our law enforcement people have seen activity that concerns them." The signs are especially ironic given that, for years, the U.S. has posted travel warnings for citizens headed into Mexico. And it's yet more evidence that authorities have lost control of U.S. land along the border, essentially acknowledging that drug- and immigrant-worker smugglers are in charge.