The footnote in that article links to an 163 page review of Sweden's relationship with Vietnam during that period.

In Sweden, the decision to support Vietnam with an official aid program occurred in the context of strong public sentiment, driven by “the image of a poor nation being ravaged by an imperious United States” (Christian Michelsen Institute, 1999, p. 23). Political debate in Sweden polarised around protecting the relationship with the US on the one hand and demonstrating solidarity with Vietnam in the face of US aggression on the other. Charismatic figures on the left of the Swedish political spectrum, notably Olof Palme, helped galvanise support for Swedish aid to North Vietnam with a series of high profile gestures.

Sweden was providing assistance to the Viet Cong, including some $550,000 worth of medical supplies. Similar Swedish aid was to go to Cambodian and Laotian civilians affected by the Indochinese fighting. This support was primarily humanitarian in nature and included no military aid.