Russia has ordered its warplanes in Syria to fly higher to avoid being shot down by anti-aircraft missiles launched from the shoulder, Reuters reported on Monday quoting the Izvestia daily. The directive comes after Syrian rebels shot down a Russian aircraft on Saturday in Idlib province and killed the pilot during ground combat.

Russia’s Defence Ministry said warplanes like the Sukhoi 25 jet would henceforth fly only above 5,000 meters (16,400 feet) to ensure their safety. The ministry said that though such a policy had been previously in force, for some reason it is no longer followed.

“We are highly concerned about the fact that terrorists own man-portable air defence systems,” Russian Presidential Spokesperson Dmitry Peskov said, according to the TASS news agency. “It poses great danger to all countries.”

Peskov said Russian President Vladimir Putin had asserted that the country’s military contingent in Syria was powerful enough to deal a “crushing blow” to militants if necessary.

However, he added that it was yet unclear how the Syrian rebels managed to procure a man-portable air defence system. Peskov dismissed Russian Senator Igor Morozov’s comments that the anti-aircraft missiles had been purchased from Ukraine.

Meanwhile, the Russian Defence Ministry said that the deceased pilot, Major Roman Filipov, had been posthumously awarded the “Hero of Russia” medal, Reuters reported. The medal is the highest honorary title in the country.