Why must spare rifles wait for lend-lease?

Can spare rifles be sent by lend-lease instead of being put on the market?

The proposed supplier needs world tension to reach 80% before the game permits that lend-lease.

Spare rifles are available for sale on the equipment market. The recipient asks for lend-lease because that route would be quicker. The proposed supplier answers that world tension must reach 80% before it becomes available. This restriction within the game delays that form of aid even though the weapons are available.