I think there's additional information to support that. Nicosia, Home to War, 213 mentions that in 8/71 the PCPJ cosponsored a trip by the VVAW's Joe Urgo to Hanoi. Nicosia, 200 mentions that Kerry had a dispute with Al Hubbard because Hubbard had gone to Moscow to accept an award, which Kerry thought was imprudent.
Also, besides Moscow and Hanoi, the VVAW sent delegations to Paris, and--according to FBI file 100-448092, Section 14, p. 54 on the Winter Soldier site--in 2/72 a VVAW meeting announced a fundraiser by the Vencermos Brigade to send trainees to Cuba.
It is true. There are several instances where these trips are mentioned. The Urgo trip mentions that several traveled with him but I don't think it states who.
Did you see the one today about Kerry and money from Communist China?