Russia will proceed with plans to provide Syria with an advanced air defense system, in part to prevent foreign “hot heads” from getting involved in the country’s conflict, a top Russian diplomat said today.

Deputy Foreign Minister Sergei Rybakov confirmed plans to deliver the S-300 system, but would not confirm when it would arrive. The S-300, one of the world’s most advanced air defense systems, could make it harder for foreign forces to carry out airstrikes inside Syria, as Israel has done this year, or to impose a no-fly zone, as some members of Congress have called for.