TEL AVIV — Israel has blocked exports of unmanned aerial vehicles for foreign militaries. Industry sources said the Israeli Defense Ministry vetoed requests by major companies for UAV exports. They said the proposed exports stemmed from political pressure by the United States. Israel’s business daily Globes said the UAV deals affected such producers as the state-owned Israel Aerospace Industries, Elbit Systems and Aeronautics Defense. Globes said the restrictions imposed by the Defense Ministry was dampening UAV and other military exports.