Maxwell was one of four Ulster players in the side

Their forward power produced tries for captain Shane Jennings, hooker John Fogarty and loose forward Neil McMillan from successful line-out drives.

Andrew Maxwell added the fourth during injury-time with a neat chip and chase.

Number eight Jamie Heaslip was named man of the match after another eye-catching performance

Ireland now have a week before they face the NZ Maori, knowing victory will book them a place in the 18 June final.

Winger Simon Keogh, Andrew Maxwell and John Muldoon all made their debuts at A level while Tom Court, the former Queensland tight-head prop and international shot putter, earned his first run in the emerald green even though he is yet to play for Ulster or club side Ballymena.

The Americans, under the charge of interim coach Peter Thorburn, were in action for the first time in nearly a year but took an early lead with a Francois Viljoen penalty.

Paddy Wallace replied in kind for Ireland after good breaks from Keogh and Heaslip had put the Eagles under pressure.

Ulster's Paddy Wallace score eight points for Ireland A

Then Ireland began to turn the screw. Matt McCullough won the lineout just inside the USA's 22, Ireland launched the rolling maul and Jennings, the Leicester flanker, got the touch down.

Ireland retained their 10-point lead heading into half-time but tempers boiled over when Fogarty and Owen Lentz were sin-binned for fighting.

Viljoen converted the resultant penalty but Wallace, having missed a simple penalty attempt, responded in the sixth minute of injury time.

The Americans were then reduced to 13 men after flanker Todd Clever was sin-binned for persistent infringements at the breakdown.

After 50 minutes, captain Kort Schubert, who plays for Cardiff, had a try ruled out in the right corner for a forward pass.

Viljoen's penalty attempt would then have put the Eagles within one converted score - but it was Ireland who went on to score.

McCullough took the lineout and McMillan was driven over by Ireland A's powerhouse pack before Maxwell notched up the fourth try - which earns them what could prove to be a valuable bonus point.

USA: F Viljoen, Palefau, S Sika, V Esikia, J Hullinger, A Tuilevuka, T Meek, M MacDonald, O Lentz, J Tarpoff, C Hansen, M Manga, T Clever, T Petruzzella, K Schubert (capt).
Replacements: M French for MacDonald (20-23 mins, 26-29, 43-50, blood sub), P Bell for Petruzzella (38-43), P Bell for Lentz (43), M French for MacDonald (64), C Osentowski for Tarpoff (77), M Aylor for T Petruzzella (77), B Barnard for Hullinger (78), B Schoener for Hansen (78), M Timoteo for Meek (79).

Ireland A: R Kearney; S Keogh, J Hearty, D Quinlan, A Maxwell; P Wallace, T O'Leary; R Hogan, J Fogarty, T Court, T Hogan, M McCullough, J Muldoon, S Jennings, capt, J Heaslip.
Replacements: D Fitzpatrick, B Blaney, D Browne, N McMillan. E Hickey, K Lewis.

Replacements: B Blaney for Muldoon (38-43 mins), K Lewis for Hearty (51), N McMillan for Muldoon (56), R McCormack for R Hogan (57), D Browne for T Hogan (68), B Blaney for Fogarty (69), D Fitzpatrick for Court (77), E Hickey for Wallace (80).