The White House expressed concern Monday over reports that Israel used US-supplied white phosphorus in attacks on Lebanon, adding that it was seeking more details about the allegations. Lebanon accused Israel of repeatedly using the incendiary weapon in October, while the Washington Post on Monday said analysis of shell fragments from one attack showed the rounds were US-made. "We've seen the reports, we're certainly concerned about that. We'll be asking questions to try to learn a little bit more," said National Security Council spokesman John Kirby.