The history of the world is, unfortunately, the history of war. Since the evolution of man—or, the dawn of man—there has been conflict. There have been conflicts over scarce resources like food, water, and oil, and there have been conflicts over clashing political systems and religious differences. Mankind has rarely known peace, and when it has occurred, it was more a prelude to yet another war. Countries have gone to war over resource-rich plots of land, and they have battled each other over god-forsaken stretches of barely-habitable land in regions like the Ogaden Desert separating Somalia and Ethiopia (1977-78). Russia and China fought battles over disputed land along their common border, China and India have battles over disputed land along their common border, India and Pakistan have fought several wars over the disputed region of Kashmir. Wars have raged across virtually every continent at one time or another. Within individual countries, civil wars and insurgencies have occurred with a similar regularity. Afghanistan has been the site of territorial and ethnic conflicts for hundreds of years, and the Arab countries of the Middle East regularly engage in armed conflict for one reason or another.
In short, war is a part of man. The United States has been engaged since its founding in wars and continues to partake in armed conflicts across the globe, including in Iraq, Afghanistan, Philippines, the Balkans, Somalia, Syria, and numerous other locales where small numbers of U.S. military advisors and special operations forces carry out sensitive military missions unbeknownst to the American public on a daily basis.
So, how does "national security" and the USA Patriot Act enhance American security? The phrase "national security" is immensely broad and covers a wide range of activities and capabilities from the thousands of nuclear-armed missiles and bombs that are meant to serve as a deterrent against foreign use of such weapons against the United States to the laws and regulations that prohibit American companies from selling militarily sensitive technologies that could wind up in the wrong hands. "National security" encompasses the training and equipping of hundreds of thousands of men and women in the armed forces, and it includes efforts by the United States Department of the Treasury and by the United States Secret Service (previously part of the Treasury Department but today, since the passage of the Homeland Security Act of 2002, a part of the newly-established Department of Homeland Security) to prevent attempts by rogue regimes such as those in North Korea and Iran to subvert the U.S. financial system through the production of counterfeit American currency. The Department of the Treasury further contributes to national security by protecting the integrity of the U.S. financial services industry, especially, banks, by monitoring for indications of money laundering (the criminal process of injecting ill-gotten gains into the formal financial system for the purposes of concealing the source of the funds) and, since the terrorist attacks of September 11, 2001, for the abuse of American banks by terrorist organizations seeking to raise and move money for the purpose of funding future attacks.
This barely skims the surface of the totality of what constitutes "national security." The Department of Defense operates the largest intelligence-gathering network in the country, if not the world, for the purpose of providing the American public, through its elected leaders, the best information available on the intentions and capabilities of America's adversaries. The U.S. Coast Guard patrols our borders to prevent against terrorist infiltration from the sea as well as to intercept as many illegal drugs from entering the United States as possible--a task of monumental proportions that has, arguably, failed.
Diplomacy is an essential component of national security. Through diplomatic negotiations with other countries, the United States has forged and sustained a series of alliances and partnerships that help safeguard the American public while ensuring allies in Europe, Asia and the Middle East of our commitment to help them defend themselves against outside attacks. The most important of these alliances is the North Atlantic Treaty Organization, or NATO. This alliance was a reaction to concerns about the military intentions of the Soviet Union following the end of World War II. Mutual defense agreements with countries like Japan, Australia, Jordan, and Israel (with Pakistan a far more problematic case of a quasi-ally with whom the United States has very serious differences regarding the India-Pakistan conflict and the role Pakistan's Inter-Services Intelligence agency has played in supporting Islamic fundamentalist movements like the Taliban in Afghanistan.
How does all of this contribute to the security of the American people? By maintaining a large, modern, technologically-sophisticated and well-trained military, the United States has, to date, been able to deter major threats our security such as existed prior to World War II. By scrutinizing commercial transactions between American companies and foreign governments that we fear may divert American technologies for nefarious purposes, this country's national security structure helps to minimize the ability of foreign militaries to develop weapons as technologically sophisticated as those in the American arsenal. By monitoring the financial system for indications of abuse by hostile countries or terrorist or criminal organizations, the national security structure of the United States protects the economy on which we all depend from destructive influences. By negotiating agreements with countries with whom the United States has shared interests, such as in the protection of the integrity of the global financial system, stemming the proliferation of technologies used in the development of nuclear, chemical and biological weapons, and working secretly with other nations' intelligence services and militaries to combat terrorist organizations and transnational organized crime, the national security structure of the United States is making America much, much safer than would otherwise be the case.
The Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001, known more popularly as the USA Patriot Act, was a direct response to the September 11, 2001 terrorist acts. Many of its provisions were individually supported by various members of Congress and by officials in the national security community before those tragic events occurred. The political climate that followed immediately in the wake of the attacks provided the atmosphere in which these proposals for strengthening law enforcement tools and forcing closer cooperation between law enforcement and intelligence agencies (previously blocked by laws that resulted from the excesses of the Nixon Administration years earlier) could be passed into law with minimal opposition.
Did the Patriot Act strengthen U.S. security and better protect the public? There are differences of opinion, but, on the whole, the answer is yes. By breaking down institutional barriers between various federal agencies, they were able to better share sensitive information so that more complete pictures of what potential threats existed could be constructed. Law enforcement, mainly the Federal Bureau of Investigation, was given more tools to conduct surveillance inside the United States, and it was these "reforms" that have been so controversial with regard to excessive use of such methodologies to monitor American citizens who should be protected against unwarranted invasions of their privacy by virtue of provisions of the Constitution of the United States. In fact, the revelations of Edward Snowden, a former government contractor who exposed tens of thousands of highly sensitive documents to the public on the surveillance activities of the National Security Agency, did shed light on potential government excesses or abuses of power. Snowden's methodology, however, no matter his actual intentions, and no matter the importance to the public of some of his revelations, seriously undermined American security by allowing hostile governments and terrorist organizations, including al Qaeda and Islamic State, to see the extent of American intelligence-gathering capabilities and to, subsequently, take measures to change the way they communicate among each other so as to avoid U.S. surveillance.
NSA overreaching aside, the Patriot Act has enhanced US security by virtue of the role it played in facilitating much greater cooperations among the myriad components of the US national security structure, especially between the FBI, the NSA and the CIA. Additionally, Title III of the Patriot Act, the International Money Laundering Abatement and Financial Anti-Terrorism Act, helped immeasurably in monitoring the flow of money terrorists use to fund their operations. While the problems of tracking terrorist money remains difficult, it is an essential part of the war on terror, and has made America a little bit safer.