and that's it for us at 5:00. we'll see you back here at 6:00 for a full hour of news. ♪ >> quija ksan denies a u.s. charge that it's behind attacks on the world's largest oil refinery. >> if the iranian regime is responsible for this attack, we're not going to stand for that. >> whether the iranians directly engaged in this has yet to be eeen. >> quijano: is a price spike at the pump next? also tonight, on strike-- why thousands of g.m. workers are trading assembly lines for picket lines. tent courthouses open for migrants in limbo as the border crisis shifts south. medicare fraud, a cbs news investigation exposes a new scheme to rip off taxpayers and tracks down a doctor involved. >> hi. i'm jim axelrod with cbs news. >> quijano: why scientists are