European Space Propulsion (ESP) Limited blamed disappointing sales for going into liquidation.
Formed by Aerojet Rocketdyne in 2012, it operated from missile maker Thales UK's factory in Castlereagh.
Its offices were opened by the former First Minister Peter Robinson.
He had expressed delight the US company had selected Belfast as its European sales base.
But it never got near its projected Â£13m annual turnover.
A spokesman for the firm said: "We had high hopes, just like the Northern Ireland ministers did.
"We thank them for their support but unfortunately expected sales just never materialised."
As recently as December, then Economy Minister Jonathan Bell talked of ESP as having "brought significant benefits to Northern Ireland".
Employee numbers never got above eight.
An American-owned aerospace firm attracted to Belfast by Invest NI and backed by the  Northern Ireland Executive is ending its local operation.