UN Peacekeepers and the ICC

As further reports of UN peacekeeper atrocities continue to flow out of the D.R. Congo, an interesting legal puzzle arises: Can those peacekeepers be prosecuted for war crimes by the ICC? The answer is probably yes, no thanks to the U.S., which has been introducing annual resolutions in the Security Council granting immunity to UN peacekeepers since 2002, but which withdrew its proposal last summer in face of opposition. Given that the UN itself has no power to discipline peacekeepers and they often have immunity from prosecution in the countries that where they are deployed, it would be odd for the ICC to have no role here. Yet putting them before the ICC is likely to discourage much needed contributions by countries like the U.S. Maybe a case-by-case exemption is needed here?