George W. Bush started the War on Terror as a response to the September 11 attacks on the United States in September 2001.
Since then, surveillance laws were passed and multiple military operations were started. The US and its allies fought wars in Afghanistan and Iraq. The US and its allies supported wars in Syria. US drones killed people in Parkistan and Yemen.
Those activities come with a cost. One the one hand, every single of Britain’s air-to-surface Brimstone missiles cost £100 000. Britain has fired at least 9 missiles in Syria so far, but not killed a single terrorist (source).
From the same article:
Two jihadists were killed with Paveway IV laser-guided bombs (20,000 US-Dollar each) and five were killed by US-made Hellfire missiles (70,000 US-Dollar a piece) fired from Reaper UAVs.
American aircraft fired at least 23,144 bombs and missiles in 2015 alone, according to data compiled by Micah Zenko, an expert on U.S. military planning and operations who is a senior fellow at the Council on Foreign Relations.
Now you should also know that one hour of a Eurofighter in air costs 73992 Euro (source).
The refugee crisis will cost Germany approximately 50 000 000 000 Euro. (source).
In 2013, American taxpayers spent 454 million US-Dollars on detention operations at Guantanamo Bay, which now holds 91 detainees (source).
We are spending much more than ever on fighting terrorism. We sacrificed a lot of our civil rights. What did we get so far?
More terrorism than ever before (sources).
To understand the effect of those missiles of the people living there, you have to be empathetic. Imagine you're in a situation where not everything might be good (or even very little might be as you like it), but you are essentially "safe". You know how you have to behave and you know what you can expect.
Now the US brings freedom to your country. The people which were in power once are not anymore. Drones could kill you on your wedding (source), when you try to bury loved ones (source). The US goes, other people get to the power. Not the ones where you know what to expect from. People who are angry at what happened. People who tell you that it was the US who killed friends or who just destabilized the country. Who tortures people (sources). Who just came there for their own interest. Who said they wanted to bring freedom, but came for the oil (sources). But who overthrew democratically elected governments (sources).
I'm not saying all of those statements are true. Yes, I'm aware that there is context missing. However, it really doesn't matter. While people being in such a situation might know more about their specific case, they will almost certainly also only have those vague ideas what is going on. To their eyes, it is the US who caused the trouble.
Why should you care?
The point I want to make here is that there is no good in fighting with weapons (only). In case you will ever be in the position to decide that, keep it in mind. In case there is an anti-war demonstration nearby, think about it.
What can we do?
Terrorism is a problem. I do understand that people don't want to just accept 9/11. Or the attacks in Paris.
And it will only get worse. Getting more advances in technology has many advantages, but a downside is that it also gets much more easy to plan and execute terrorist attacks. There is no way to live in a free high-tech world and preventing people from being able to execute horrendous attacks.
Especially, simply going to war isn't solving that problem. We have to understand why people are doing what they are doing. Don't prevent the attack, make people not having reasons to make attacks.
This is much harder. It needs a deep understanding of what drives people. It needs empathy, diplomacy, support. Contact. Showing people that you care about them. That achieving basic goals to help them lead a better live is worth the money (for example: below 35-76 billion US dollars for the millennium goals (source) compared to 468 billion US dollars for 2001-2011 in Iraq).
Achieving those goals might include sending the army. But not as the main thing to do, but as a supporting force. To protect people who help building lasting structures.
Stop war. Think what we want to achieve, think of the most likely outcomes of your foreign policy steps. From the beginning of your foreign policy until you leave the country on their own. Think of other peoples interests, not only of yours. Because win-win is awesome.