Most Americans have little understanding or concept of Iran's size in terms of geography or population. The ethno-religious make-up of the sprawling Mideast/West Asian nation is also deeply important, given the US is already talking about arming and supporting some kind of Kurdish-led anti-Tehran ground operation. 

Suffice it to say, Iran's population is more than double (over 90 million people) that of neighboring Iraq's. Iran is also the size of almost half the European continent. All of this is crucial for attempting to visualize what American military escalation there might mean, given the Trump White House has not ruled out American boots on the ground amid the unfolding 'Operation Epic Fury'. Consider: the US spent two blood-soaked decades occupying Iraq (again, significantly smaller than the Islamic Republic). Russia has spent over four years on its military operation in Ukraine, and Iran dwarfs Ukraine in size.

And here's Iran's size overlaying the European continent.

Next: Size of Iran vs. Alaska (with the continental USA for scale). Imagine a war that covered some nearly one-third of the continental United States, and also imagine an outside force trying to pacify a population of 90 million within that vast geography. 

Iran and Alaska are similar in massive land expanse: 

• Alaska: 1.723 million km² ≈ 665,000 mi² (about 17.4% of USA)

• Iran: 1.648 million km² ≈ 636,300 mi² (about 16.7% of USA)

• USA: 9.867 million km² ≈ 3,810,000 mi²

Another look: Iran is far bigger than Texas.

It is also significantly bigger than Iraq.

Importantly, the single deadliest Middle East war in the modern-ear was the Iran-Iraq war. From 1980 to1988 these enemies sharing a common border fought a ground and artillery war to stalemate. It was an utterly disastrous war of attrition, and at that time the United States actually covertly supported Iraq under Saddam Hussein in order to weaken Iran.

But Iran persisted through even that, which gives some idea of what it might be able to endure while facing a war for its very survival and existence with the US and Israel.

The number of casualties in the Iran-Iraq War ranges from 1,000,000 to twice that number. The number killed on both sides was perhaps 500,000, with Iran suffering the greatest losses. It is estimated that between 50,000 and 100,000 Kurds were killed by Iraqi forces during the series of campaigns that took place in 1988. —Britannica

TEHRAN city size: Comparable to New York City.

Any ground invasion necessitates exhausting, grinding urban warfare including room and building clearing by infantry troops.

Many American veterans of the Iraq war have stories of grueling building clearing operations in places like Baghdad or Fallujah which could take five to eight hours to carefully and systematically clear a single large city building. Marine veterans would tell you large building room-clearing is the most physically demanding and ultra-risky task of any infantryman. 

The Iranian capital of Tehran has a population of approaching 10 million, while the greater cosmopolitan area has some 16 million people. 

Tehran's population is estimated at 9.5m (16.8m including the metropolitan area). Its size and density are comparable to New York City: regionally, it is on a par with Cairo and Istanbul. -Middle East Eye

Tehran: A vast, modern cosmopolitan city, packed with civilians, now under US-Israeli 'shock and awe' style bombardment.

As US-Israeli military planners know full-well, Iraq had descended into sectarian chaos soon after the 2003 US invasion, and a similar ethno-sectarian scenario could play out in Iran, though the Persian people tend to have greater national unity compared to that of neighboring Iraq.

The CIA and Mossad are reportedly already exploring trying to peel off one of Iran's large ethnic minorities, like the Kurds.

It just so happens that the Kurdish-dominant far northwest is filled with mountainous, rocky terrain.

This means any effort to launch some kind of ground civil war or unrest against the Iranian state by Kurdish proxies would surely be difficult, slow, and grinding - and terrain might be in Tehran forces' favor.

We will leave off this brief visual tour with a quote that commonly gets attributed to one well-known American author, who famously wrote the book aptly titled The Innocents Abroad.

"God created war so that Americans would learn geography."

― Mark Twain

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What a ground invasion of any country means: brutal house-to-house combat...