WASHINGTON — Vice President Joe Biden said Monday that the killings of the top two al-Qaida figures in Iraq are "potentially devastating" blows to the terror network there and proof that Iraqi security forces are gaining strength. Biden came before reporters in the White House briefing room to draw added attention to the results of a joint U.S and Iraqi operation — a nighttime rocket attack on a safe house near Saddam Hussein's hometown of Tikrit. Abu Omar al-Baghdadi and Abu Ayyub al-Masri were killed. Iraqi Prime Minister Nouri al-Maliki first announced the deaths at a news conference in Baghdad and showed reporters photographs of their bloody corpses. Biden referred to those killed as former leaders of al-Qaida in Iraq who "plotted, planned and executed terrorist attacks" against Iraqis and Americans.