Eighteen years ago, al Qaida terrorists who had entered the United States attacked the United States in the United States.
In response, we launched a war on the other side of the world.
The lead inspector general for Operation Freedom's Sentinel -- the current name for the war in Afghanistan -- described that war's genesis and original purpose in his latest report.
"On October 7, 2001," said that report, "the United States launched combat operations in Afghanistan under Operation Enduring Freedom to topple the Taliban regime and eliminate al Qaida, the terrorist organization responsible for the September 11, 2001, attacks on the United States."
U.S. military action did remove the Taliban from power in Kabul, but it did not destroy the Taliban. It did kill or capture many al Qaida terrorists, but it did not eliminate al Qaida.
In 2003, after invading Iraq, then-President George W. Bush converted the strategic aim of the United States in Afghanistan, Iraq -- and, indeed, the world -- into an ideological enterprise.
"We are committed to freedom in Afghanistan, in Iraq, and in a peaceful Palestine," Bush said, standing on the deck of the U.S.S. Abraham Lincoln off the coast of San Diego.
"The advance of freedom is the surest strategy to undermine the appeal of terror in the world," Bush said. "Where freedom takes hold, hatred gives way to hope. When freedom takes hold, men and women turn to the peaceful pursuit of a better life. American values and American interests lead in the same direction: We stand for human liberty."
Two years later, Bush made this doctrine the centerpiece of his second Inaugural Address.
"(I)t is the policy of the United States to seek and support the growth of democratic movements and institutions in every nation and culture, with the ultimate goal of ending tyranny in our world," he said.
In 2011, two years after Bush left office, the United States finally tracked down and killed Osama bin Laden.
He was in Pakistan -- not Afghanistan.
When President Donald Trump took office in 2017, the Afghan war was in its 16th year. That August, Trump announced a new South Asia strategy.
In announcing it, he rightfully criticized the manifestly futile nation-building policy promoted by Bush.
"I share the American people's frustration," Trump said then of the Afghan war.
"I also share their frustration over a foreign policy that has spent too much time, energy, money, and most importantly lives, trying to rebuild countries in our own image, instead of pursuing our security interests above all other considerations," he said.
Trump then defined what he believed "victory" would mean in Afghanistan.
"From now on," he said, "victory will have a clear definition: attacking our enemies, obliterating ISIS, crushing al Qaida, preventing the Taliban from taking over Afghanistan and stopping mass terror attacks against America before they emerge."
The first four things Trump mentioned here should only matter to our government if they lead to the fifth: stopping attacks against the United States.
ISIS -- the Islamic State group of Iraq and Syria -- did not emerge as a significant force until we invaded Iraq and overthrew Saddam Hussein. Now with Trump in his third year in office, ISIS' Khorasan branch has become a force in Afghanistan -- where both the Taliban and its al Qaida ally are still active.
In its latest report to Congress on this 18-year-old war, the Department of Defense summarized the situation on the ground.
"Terrorist and insurgent groups continue to challenge Afghan, U.S., and Coalition forces," said the DOD report.
"During this reporting period, ISIS-K made territorial gains in eastern Afghanistan," it said. "Regionally the group continues to evade, counter, and resist sustained CT (counterterrorism) pressure."
"While ISIS-K remains operationally limited to South and Central Asia," it said, "the group harbors intentions to attack international targets.
"Al-Qa'ida (AQ) and Al-Qa'ida in the Indian Subcontinent (AQIS) routinely support, train, work, and operate with Taliban fighters and commanders," said the report.
"AQ maintains an enduring interest in attacking U.S. forces and Western targets," it said.
President Trump this week ended negotiations with the Taliban after a Taliban suicide bomber killed an American soldier in Kabul.
The DOD report concluded that even if those negotiations had succeeded, they would not have stopped al Qaida, ISIS or even current members of the Taliban from continuing their activities in Afghanistan and posing a threat to the United States.
"Even if a successful political settlement with the Taliban emerges from ongoing talks, AQ, ISIS-K, and some unknown number of Taliban hardliners will constitute a substantial threat to the Afghan government and its citizens, as well as to the United States and its Coalition partners," said the DOD report.
"This enduring terrorist threat will require the United States, the international community, and the ANDSF (Afghan National Defense and Security Forces) to maintain a robust CT capability for the foreseeable future," it said.
It is a safe prediction that even if Trump serves two terms, the Taliban, al Qaida and ISIS will still exist and still be present in Afghanistan when he leaves office. It is a safe prediction they or their ideological offspring will outlast Trump's successor and his successor's successor.
The duty of our president is not to eliminate them from this Earth -- or even from Afghanistan -- but to prevent them from attacking Americans.
Terence P. Jeffrey is the editor in chief of CNSnews.com.