I think that commitment is very, very important. Look at past recent Presidents and see who had the committment to actively defend the country (Johnson, Nixon, Reagan, BushX2) and who didn't (Ford, Carter, Clinton.)
An excellent example of the importance of committment to defense was the Iranian Hostage crisis. Carter bluffed and blustered, and the Iranians knew he had no backbone so they did nothing. Once Reagan was elected, the hostages were released because they knew that Reagan wasn't about to brook any nonsense from them.
Another example was the invasion of Kuwait in 1992. Hussein didn't invade until after he had been told (wrongly) by a US diplomatic official that the US wouldn't respond to an invasion. Had that impression not been given, Desert Storm would have never happened.
Lastly, Bill Clinton's repeated use of using equivalent force when dealing with terrorists was an invitation to disaster. Rather than use escalated force, he chose to match the destruction of our assets with an equal destruction of theirs. That made the military strength of groups like Al Quada the equal of the United States, which gave Osama all the power he needed to recruit personnel and raise money.
Kerry's repeated statements that he would seek international cooperation before engaging in military operations, when many of the key international players are in the pockets of the leaders of the countries we would be operating against, does little to show committment. The countries that Kerry felt were so important to have on our side... France, Germany, Russia... all had deep financial ties to Iraq, and would never have given us a blessing to attack. Who else do they do business with? Syria, Lebanon, Libya, North Korea, Iran... how much support would these Allies be in those cases???
A strong, demonstrated, committment to defense is an excellent deterrent to agression. A weak committment is a very weak deterrent... just ask Osama Bin Ladin.
