That's according to a Guardian report that claims Van Gaal values Vermaelen's adaptability - he can play at centre-back or left-back.
Having spent £27m on young England full-back Luke Shaw and with Patrice Evra heading to Juventus, Van Gaal wants experienced cover. And in Vermaelen he believes he's identified a player who can also compete with Phil Jones, Chris Smalling and Jonny Evans for a starting place in central defence while also backing-up Shaw when required.
Shaw is number one
The former-Southampton defender will start the season as the club's first-choice, but Van Gaal had planned to rotate Evra into the team. With that option set to be taken off the table, the French international is negotiating a move to the Italian champions, United need a replacement.
Van Gaal could splash out big-money on another specialist, and United officials have discussed a move for Wolfsburg and Switzerland star Ricardo Rodriguez. But it doesn't make much sense spending more than £40m on two players who play just one position.
Instead, Van Gaal plans to swoop for a player who can fill two roles, strengthening his hand at centre-back and left-back with the addition of the £12m-rated Vermaelen.
The Belgian international is looking for first-team football, and would primarily be viewed as a centre-half at Old Trafford, having fallen behind Laurent Koscielny and Per Mertesacker at the Emirates Stadium.
United transfer business
On paper it makes sense for United, a club with other holes to fill despite the addition of Ander Herrera and Shaw. Van Gaal is looking at Arturo Vidal and Angel Di Maria among others, which makes it difficult to imagine him committing funds to another full-back as well.
But Vermaelen struggled to crack the Arsenal team last season, which has to raise questions for United fans. If he is not good enough to start for the Gunners, is he really going to improve United's defence?