From hapiness to sadness

Since the president Obama announced last Sunday the death of the terrorist Osama Bin Laden most of the people in The United States have been very happy. Some people is happy because they think that is justice for their death family members. Some other people is happy because they feel now is nothing o be afraid of. However, that is not completely true. There is a big possibility of revenge by the Al Quaida terrorist group. In fact, today the group confirm the death of Osama Bin Laden the leader of the group and they said "people of The United States will pass from the happiness to the sadness". In my opinion, this is really scared. We know what this group is capable to do. In fact, the government found on the documents of Osama that they were planning to attack the trains of the U.S on the anniversary of 09/11. Nowadays we are noticing that the airports, train stations, and many important places have more secure than normal. So my questions are: Is this only precaution? Does the government know more than we know? Should we know everything that government knows? I think we sould.