Nearly 16 years ago, I was a first-year grad student at the University of Texas at Austin and my Air Force ROTC class ended early when news broke that two airliners had crashed into the World Trade Center. We watched in horror as death and panic engulfed New York. And it was bewildering that the Pentagon could be attacked at all.

America's long wars

Fast forward to today and Afghanistan and Iraq are America's longest wars. Generations of taxpayers will be on the hook for trillions of dollars in war spending — numbers too massive to comprehend. Coalition families have also paid dearly.

To date, over 4,500 U.S. soldiers have sacrificed their lives in Iraq and more than 2,400 in Afghanistan, with tens of thousands more wounded physically and/or mentally — my brother being one of them.

While two-thirds of Americans are worried about fighting another war, the mission to defeat terrorists is not over. Radical Islam and pariah nations continue to threaten American and global security. Thus it's crucial for the United States and her allies to continue the fight against jihadist thugs who torture and kill innocent people on behalf of a twisted cause. Moreover, we cannot allow cynics, academics or the media to lull us into complacency, or to shame patriots who rightfully want to protect our homeland.

Moral relativism is a nice theory from the Ivory Tower, but it will never protect us from the pop of an AK-47 machine gun or rocket-propelled grenade.

As Abraham Lincoln said, "It is rather for us to be here dedicated to the great task remaining before us -- that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion -- that we here highly resolve that these dead shall not have died in vain …"

America's responsibilities in a small world

Yes, we have economic problems at home, but we cannot abandon the mantle of leadership in a world that continues to be attacked by Islamic extremists and state actors like Iran, North Korea, and even China (in the Spratly Islands, Himalayas and other disputed territories) and Russia (in Ukraine and Crimea).

Jihadists recruit people in the name of religion. But the Quran actually forbids the killing of innocents and discourages the imposition of Islam to non-believers. The Quran prohibits the torture of prisoners and mistreatment of fellow Muslims. Yet it's telling that Muslims are seven times more likely than non-Muslims to be victims of terrorism.

It's clear that ISIS, Al Qaeda, the Taliban and Iran's mullahs are more interested in grabbing power and intimidating their neighbors than advancing what the prophet Mohammad intended as a peaceful religion.

Deterring our adversaries

Here are some of America's responsibilities abroad. First, we need to keep the Korean peninsula in check. If Kim Jong-Un develops miniaturized nukes and ICBMs, not only can he threaten the U.S. mainland but Iran will most assuredly purchase these weapons from North Korea, which desperately needs the cash. Think of the consequences. Kim's ICBMs can reach the Pacific West Coast in under 30 minutes and hit New York or D.C. in 40 minutes. To those who accuse conservatives of being warmongers, let that sink in.

Our foreign policy must be crafted from facts — not media spin or political demagoguery.

Second, our European allies need to assume more of the burden of peace and prosperity. The United States pays more than 70 percent of NATO's annual spending and that's both unacceptable and unsustainable. With $20 trillion in national debt, America needs help in stabilizing flashpoints around the world. More defense participation is needed from Germany, Spain, France, Scandinavia and other NATO countries.

And in Asia, allies like Japan, South Korea, Australia and nearby countries can do more militarily to improve security in the western Pacific. More defensive capabilities from these allies would help U.S.

efforts in countering China's aggression. Chinese leaders do not respond to diplomacy — they understand force and self-interest.

They need to stop nuclear proliferation

If Iran successfully develops its nuclear and ballistic missile programs, these weapons can hit Berlin or London in less than 15 minutes. NATO members should invest in missile defense. And a stronger military posture from European nations will check Russian aggression in the east such as Ukraine. Ideally, a more robust NATO would free up the U.S. military to transfer troops and aircraft (from Europe) to the Middle East, in places like Syria and Iraq. ISIS may be close to defeat but other Islamic terror groups are poised to take its place.

In other words, Jihad won't end just because ISIS lost.

The masks of evil may change, but the true face of the enemy remains constant: violent extremism. These thugs are irrational and they'll keep attacking in the delusion that they'll get 72 virgins in the afterlife. America should never disengage from the most volatile region in the world. Barack Obama did so with disastrous consequences.

Islam isn't the enemy — armed extremists are

It's unfortunate that many in the Middle East view Americans, Israelis, Christians and other groups as infidels. Such intolerance is the root cause of most violence in the region. It's unreasonable for progressives to label President Trump as an Islamophobe. Where do you ever see Christians killing large swaths of Muslims?

Doesn't happen. Rather, it's the extremists who strap suicide bombs to their chest and terrorize the civilized world. Unfortunately, liberals' rejection of the facts prevents honest debate from taking place in the media and academia.

Today Iran, its proxy militias and Russian partners are dominating large areas of the Middle East. More U.S. forces (ideally relocated from Europe) would counter influence from Iran, Shiites, radicals and Russians. Hezbollah, Hamas, Houthis and other terror groups not only destabilize the region, they threaten key allies such as Israel, Saudi Arabia, Turkey and Jordan. Iran routinely proclaims its goal of destroying the state of Israel, yet an increasingly anti-Semitic media ignore such risks in its (fake) news coverage.

It's the job of U.S. forces to minimize threats while they're small, and to prevent security risks from metastasizing into un-curable cancer.

There's political opinion and there's moral duty

Many no longer support the War on Terror — and that doesn't make you un-American. Our right to free speech is what makes our country great.

Many did not support invading Iraq. Many opposed President George W. Bush, and the vast majority of conservatives opposed Barack Obama. But whatever your political stripe, know this: America has a moral duty to prevent terrorists and outcast nations (such as Iran and North Korea) from acquiring or further developing weapons of mass destruction. This obligation is greater than any opinion.

These thugs could one day repeat the horrors of September 11 and kill thousands of Americans by using biological, chemical or nuclear weapons.

The nuclear sword must never be allowed to draw humanity's blood, or to hold hostage the fate of the entire civilized world. Our generation cannot allow mankind to descend to a second Dark Ages. Only America and its allies can fight this cause. You'll never see China, an emerging superpower, undertake this moral crusade. The Chinese are too busy pursuing selfish ends of wealth and resource grab.

Liberals may whine and complain about America being too strong or too involved overseas. But when we're militarily weak, such as when Barack Obama or Jimmy Carter were president, the world descends into chaos and violence.

In reality, terrorists and pariah states merely use diplomacy to stall for more time so they can amass an arsenal and grow their armies, and secondly, to blackmail America and her allies by asking for money and other concessions at the negotiating table.

Power projection prevents more attacks

In the late 1990s, President Bill Clinton paid billions of dollars in ransom to North Korea in the hope that it would de-nuclearize the peninsula. Look where that got us. When you give resources to the enemy, you merely give your adversary the means for your own destruction.

Obama withdrew U.S. forces out of Iraq — against the advice of all his generals and even Hillary Clinton. Look where that got us. ISIS grew significantly.

Iran's Shiite influence overtook Iraq. Russia deployed its military to Syria. Turkey, a NATO country, succumbed to Iranian and Russian influence. There's Hezbollah in Lebanon; Hamas in Palestine; Houthi rebels in Yemen — they're all anti-American and backed by Iran. And they all wreaked havoc soon after Obama's feckless withdrawal. Idealism may win elections but sound foreign policy is derived from realism.

Furthermore, weakness is provocative because it invites a bully to attack. To paraphrase what President Ronald Reagan said, strength encourages peace because it deters a would-be aggressor. Our enemies understand only one thing: bloodshed and the tools for delivering more of it.

Recall the shock when the World Trade Center buildings fell on that Tuesday morning on September 11, 2001.

Jihadists started a war with the civilized world by killing or wounding 10,000 innocent Americans. Let's continue to fight them on their turf and eliminate their capability to strike us again. Each time the calendar flips to 9/11, we appropriately remember the sacrifices we've made to protect our freedoms, our families and our way of life.