[SPAM] The attack comes 2 days after at least 15 civilians were killed by U.S. forces

"We see two serious problems with these proposals," Lavrov told reporters at the news conference with Rice, Gates and Serdyukov. He said the two sides still disagree about the threat to Europe and complained that the negotiations with the Poles and Czechs were continuing.The United States has repeatedly rejected Russian demands to freeze U.S. negotiations with Poland and the Czech Republic, and Rice did so again Friday, said three senior U.S. officials present at the sessions with Rice, Gates, Russian Foreign Minister Sergey Lavrov and Defense Minister Anatoly Serdyukov.U.S. military planners quietly have stepped up a review of alternatives in case the Turkish government restricts U.S. access to Turkish airspace or cuts off access to the air base at Incirlik, Turkey, CNN has learned.Rice said the ideas that she and Gates presented are "conceptual at this point" and would be handed to experts to consider further.Initial reaction from Lavrov and Serdyukov, though, was less gra!  cious.The attack comes a day after a security official in Iraq's Salaheddin province said that a U.S. military operation Thursday night killed 20 civilians, most of them women and children. Full storyAs part of that plan, experts from all nations covered by the system would be based at missile defense facilities to try to improve coordination and transparency.The U.S. military estimated Thursday that 15 civilians were killed by coalition forces in the operation targeting senior leaders of al Qaeda in Iraq. The military said the terrorist group put the victims in harm's way.Serdyukov agreed.U.S. Air Force planes prepare to take off in November 2001 from the air base at Incirlik, Turkey.