I think some of it also comes from the IRA and PLO, as well as various other European independence groups such as ETA having a lot of similar backers and simila

I think some of it also comes from the IRA and PLO, as well as various other European independence groups such as ETA having a lot of similar backers and similar problems to solve and so working with each other. The Soviet Union, Libya, Castro, etc backed them all and to some extent they helped each other out.