A Muhammad Atta or Abu Abbas type would be up to it - for the glory of Allah and his true Prophet, blessings and peace be upon him, of course.
Well the enemy has shown that they are evil enough to do it if they could do it. But the question is...CAN they do it? And I think the answer is no. But someday they may be able to do it so we have to be prepared for the future. But I don't think it is an immediate threat. So I am not going to worry about it at this time.