Theorycrafting, obviously. Generally the first question would have to be ‘what do our armed forces need to be able to do?’.

**Assumptions: **all already planned procurements do continue. Belgium has a GDP of about 644.8 billion €. We were at about 1.3% of GDP spent on military.
Let’s assume we’ll have to increase well beyond 2%, to around 2.5-2.6% due to recent events. (In my opinion, 3-3.5% is not needed either).

In general, from a military budget, about 20-30% goes to procurement. For thought experiment, I take the GDP above, take 1.3% (the doubling of defense budget), x 10 for the next 10 years, x 30% (at least 30% of new budget should go to procurement.
I arrive at **25 billion € for acquisitions over the next 10 years. **

What could Belgium acquire for this money, from EU?

I’d say Electronic Warfare & Cyber defense can easily eat 1-2 billion right from the start.
Our defense minister wants to buy more F35’s, I’d rather not.
I’m also not convinced an extra frigate (quite large for us) makes sense.
Note that Belgium is extremely risk-averse when it comes to military casualties.

Naval option :
Dutch submarines. 2 ships. At approx 1.5 billion each, that comes to 3 billion. Belgium operates in close co-operation with the Dutch navy. The new Dutch submarines will be fewer (4 ships) due to high cost.

An extra patrol vessel: 30 ish million. Relatively ‘peanuts’.

2x new European patrol corvettes. (combat variant?) Estimated at 300 million each, for 600 million.

The above pushes 3.63 billion towards the navy, let’s round it out to 4 (guaranteed in practice the price will tend to go up). Less than 20% (but there will need to be support budget of course also, this is just looking at procurement).
Corvettes & Minesweepers are maintained in Belgium.
Frigates in the Netherlands, and so would the submarines need to be as Belgium has no experience in this area.

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The Belgian land army. Poor sods.
Current: Nothing with tracks. Little artillery just recently. Manpads for anti-air.

a heavy mechanized brigade with artillery and anti-air support seems like a bare minimum for the economical size of Belgium. (nr 7 in EU!).
The Griffons are too lightly armed for the frontline.

This would require at least about 120 IFV’s. Ideally with the 40mm CTA as the Jaguar has.
And 60 Main Battle tanks, if we want this capability.
Because we are coming from 0, and we are not sure what capability will be needed, I’m going to assume an oversized brigade.

120 Wheeled IFV’s. Options include: VCBI2, the Patria AMV (with a 40mm CTA turret to be developped), and others.
120 at approx 5 million/unit = 600 million €.

120 Tracked IFV’s. Examples the CV90, the South-Korean K21 (Redback for Australia, and I believe Polish ), the Lynx, and others.
We’ll assume a cost of about 8 million/unit. 120 x 8= 960 million €. Round it to 1 billion.

60 Tanks, about 15 million each. 90 million.
60 other ‘gun platforms’. These could be wheeled, to make a ‘wheeled sub-brigade’ or lighter tracked vehicles for max mobility. We’ll count these as 10 million each, for 60 million.

Anti-air: both short range and medium-long range anti-air would be needed.
The 40mm CTA cannon might serve. If not, the 30 or 35mm ‘oerlikon’.
Then, there are the various CAMM-based, Iris-T based, and/or Aster based options.

2 SAMP/T batteries would run about 1.5 billion.
But this would just be for the brigade. 4 batteries for Belgium seems a minimum to me, given the airports, Brussels, the naval ports,…
So: a casual 3 billion.
We’ll add in an assumed cost of 1.5 billion on various short(er) range weapons.

Artillery: Caesars, let’s assume 8 million per unit.
2x8 would be 8x16 million = 128 million.

1 rocket artillery battery. If using the Chung Moo system, assume about 150 million cost.

Various support vehicles: if it can be done by a Griffon, use a Griffon, we’re buying 100’s of them already.
Still, towing capability, engineering vehicles (de-mining!), command & control, communication,…

Let’s round it to an extra 500 million-1 billion of ‘varia’.

This mechanized brigade would cost (vehicles only):
600 mill (wheeled IFV’s)
1.000 mill (tracked IFV’s)
90 mill (tanks, absolute minimum nr) 60 mill (wheeled gun platforms)
4.500 mill for anti-air (includes 2 batteries for Belgium territory)
128 million gun-artillery
150 million rocket artillery
750 million ‘support’ of all kinds.

Sum: 7.3 billion approximately.

So:
25 billion

• 2 billion on Electronic Warfare & cyber
• 4 billion to the navy
• 7.3 billion to the land force.

Still leaves 11.7 billion in leftovers.

Of course, there will need to be infantry equipment, munitions, and so fort.
But that is quite a royal sum.

We’ll say we can freely use half of the leftover, about 6 billion, on a bit of a splurge.

Drones
drones everywhere.
3 billion worth (including weapons)
After FCAS/GCAP are fully developped, the air force would once again get a bigger share of the funding at that point, and get even more drones.

Long range missiles
a la Long Range Hypersonic Weapon.
We’ll say we develop a European one, with a 50 mill € unit cost.
For 3 billion, Belgium could buy 60.
That’s a significant capability to casually add.
Even at 100 mill per unit, it’d be 30.
If other European countries would do the same (we cannot fund such missile alone…), Europe would reach into the high hundreds, if not thousands of such missiles.
Deterrence achieved I’d say.
Bit of a role-swap with Russia whom tends to have historically, missile superiority, a bit of a copy from China (oh my, how the turn tables…), I’d rate such capability of having a (modest) missile stockpile, above adding an extra 8 F35’s. (the planes cost 80-ish million, but that doesn’t include weapons, and they need pilots etc).

I’d love to read alternate takes on a hypothetical Belgian (or your local countries’) military buying spree.