

On May 25, 1953 the Grable test under Operation Upshot Knothole fired the W9 nuclear artillery shell over 6 miles downrange at Frenchman’s Flat detonating at 15 kilotons. The artillery shell weighed roughly 803 lbs. This was 1950’s technology that could still fit in the back of a pickup truck and level a city. I’m sure they’re a lot lighter and a lot more powerful today. So, yes. If we could do it in '53 we could definitely do it today, but with orders of magnitude more destructive force and likely lighter weight.
Edit: I did some more digging. For instance, the W88 warhead aboard MIRV’s on nuclear subs today have an explosive force of 475 kilotons with a mean average weight of 400 lbs for comparison. Though, most of that weight is probably shielding for reentry, so you could probably cut it back significantly if you’re just putting it in a car trunk.
It is the year 0079 of the Universal Century. A half-century has passed since Earth began moving its burgeoning population into gigantic orbiting space colonies. A new home for mankind, where people are born and raised.
And die.
Nine months ago the cluster of colonies furthest from the Earth, called Side 3 proclaimed itself the Principality of Zeon and launched a war of independence against the Earth Federation. Initial fighting lasted over one month and saw both sides lose half their respective populations. People are horrified by the indescribable atrocities that had been committed in the name of independence.
Eight months had passed since the rebellion began. They are at a stalemate.