The article itself seems to be saying that this "defense boost" was something Denmark was already planning on doing, and Trump's remark really just coincidentally came just before they actually signed off on it. The Danish defense minister, Troels Lund Poulsen, called the timing an "irony of fate".

The article describes the boost as encompassing the following:

1. Two new inspection ships.
2. Two new long-range drones.
3. Two new dog sled teams.
4. Increased staffing at Arctic Command.
5. Upgrades to a civilian airport to be able to handle supersonic fighter jets.

It's worth noting that the Arctic Command carries out a lot of tasks other than just defense per se, and as SoyViking pointed out, Danish military buildup in Greenland is largely due to anti-Russian paranoia rather than anything to do with Seppoland.