Why does the US still maintain so many military facilities in Western Europe?

Question

The US maintains a lot of military facilities in countries like Germany, the Netherlands, Belgium, etc.

This doesn't make economic sense. The US military expenditure is on trajectory to reach a Trillion dollars, and maintaining these bases is just a drain on the treasury.
This also doesn't make geopolitical sense anymore. These countries are firmly in the US sphere of influence, and the frontier with Russia has moved further East - to the Baltics, Poland, Romania, etc.
During Trump Presidency, there was incentive as well - they wanted Europe to pour more money towards military. Reduced US presence would have pushed them towards that.

Why didn't/doesn't the US reduce the number of military bases?

Answer 1

There's an important word you're missing: logistics.

The US has to project its power. To do that, you need to be able to move not just troops, but equipment and supplies. But you don't just move those troops and supplies without some place to offload and stage them.

Take Ramstein Air Base. It's the headquarters for NATO. It's also a major staging ground for Europe, Africa and the Middle East.

It serves as headquarters for the United States Air Forces in Europe – Air Forces Africa (USAFE-AFAFRICA) and also for NATO Allied Air Command (AIRCOM).

This also means your staging areas are decently far back from any front line fighting. You wouldn't want a ground invasion force to be able to attack or capture it easily.

Answer 2

@Machavity rightly notes that logistics are one reason.

As another example of that, wounded U.S. soldiers in the Iraq, Afghanistan, and the Balkans were frequently transported to U.S. military bases in Germany, which had more advanced military hospitals than the facilities available in forward bases in country and U.S. ships in the region. Returning to a U.S. hospital would have taken roughly nine more hours which could be a matter of life and death, and providing hospital services for U.S. military personnel in conflicts which a host nation was not a part of might make it a party to the conflict where the soldiers were injured.

Another factor is that by placing a U.S. base in the territory of an ally in Europe, the U.S. is basically making it inevitable that any attack by Russia or its allies on that country is an attack on the United States. This makes the U.S. commitment to defend its NATO allies if they are attacked more credible, both to NATO allies who are protected by this promise, and to Russia or other potential aggressors.

Since the U.S. has a large nuclear arsenal, this means that an attack on a country with a U.S. base in it, risks a nuclear escalation by the U.S. against the aggressor.

Answer 3

Logistics, and detailed military considerations aside, the key concept to take into account is US security: there are economic and political influence benefits from having significant allies in Europe and globally (and, to some extent, counteracting the waning global projection capabilities of Russia).

Many of the European allies are however not entirely committed (i.e. consider their typically < 2% GDP defense budgets) to maintaining armed forces and the US is running a calculated operation balancing out its costs vs benefits. Without a strong US presence, NATO might not exist in the same form and the US may not benefit as much from having them, and the EU, "in its corner".

Why the United States Still Needs Ground Forces in Europe | RAND

The presence of U.S. forces draws additional critical, albeit more abstract, benefits. The scale of U.S. forces on the continent is a key ingredient to U.S. influence in NATO institutions. Without the glue of U.S. strategic thinking to anchor the alliance, NATO would probably struggle to develop coherent military policies and plans. If the United States were to diminish its own contributions, it would also undermine the message the United States is currently giving to its allies that greater military investments are needed to maintain security in Europe.

Quoting RAND again, keep in mind that deployment cost are only a fraction of overall defense costs (you still pay gear, salaries and housing, though you forego local basing benefits to your own economy).

The cost of keeping U.S. forces in Europe must also be matched against the benefits that the United States might recoup from reducing its troop count. Even advocates of reduction agree that the concrete costs of the United States' European presence are small—on the order of hundreds of millions, not billions—relative to the overall defense budget. Further, that the primarily light infantry and armored formations present in Europe would probably not add as much value in the primarily naval and air contingencies imagined in a conflict with China.

Not sure about Europe but South Korea foots a considerable part of the bill for the US troops there (and see next paragraph about ICBMs).

Another factor is that ICBM interception technology is often strongly geared toward "boost phase intercept", nearer adversarial launch points. That was the rationale for bases in Poland.

Answer 4

I agree with all the points @Machavity and @ohwilleke make, they're the most important/significant.

Throwing another point onto the pile I'll mention economics. A military base, both in the US and outside, has local economic impact. Goods and services are acquired using US federal dollars. The base is a form of foreign (or domestic) aid.

While the military has say mechanics and cooks and police it's often the case (for whatever reasons) that many or even most of these tasks are performed by local, i.e. civilian, personnel especially in peacetime. Similarly things like food or construction materials could be shipped from the US (or another state/city) but it's often quicker and/or more cost effective to purchase them locally.

As @ohwilleke mentions the bases are used, and effectively required, as part of the US NATO membership. This is still relevant even though the Cold War is "over", just being there is a form of deterrence. The circumstances of the bases being there are of some importance as well -- the origin of many/most of them is WW2. While the possibility of hegemony by the states where the bases are sited presently is low and/or nonexistent the mere presence of them sends a signal and a historic reminder that is in and of itself useful and valuable, i.e. is geopolitical strategy.

Answer 5

As other said, early interception of ICBM is one of the goals, but these intercepting systems require very limited maintenance and they do not require such a large deployment of troops.

What require a much larger logistics is the deployment of nuclear bombs and their vectors, and this is the basic reason for so many large basis in Europe. However, in proportion to the population, Germany, Italy and Portugal are not that different than South Korea and Japan (see map here). Conveniently for the US, the countries having frictions with the US political estabilishment (Russia, China and Iran) are located close to these bases.

Then there is an obvious political answer, i.e. that European Union is an US colony, with some limited political degrees of freedom given by the nuclear weapons owned by France and UK (ehm ... not anymore the UK ones).

This is evident even in the reasoning behind some of the EU monetary policies, where the parity of EUR with USD was a goal and was celebrated by many progressive politicians (a strong example was the Italian governor Renzi).