It's not about the tanks, although they do not need them, no matter if they're old, or new. It's about the fact that they are allowing the Russians to build a military signals intelligence site to spy on the United States, in exchange for those tanks. Nicaragua is positioned very uniquely as well, giving the Russians an opportunity to cause a lot of mayhem, if they actually ensconce themselves in there significantly. They can hold sway in both directions, all the way from Argentina to Mexico. This won't be allowed to go forward, and the Nicaraguans will be corrected.