Smuggling routes from Iraq, Libya, Jordan, Yemen and the Lebanon have helped provide the groups with weapons. At the same time, rebels have targeted military bases and ammunition depots.
Channel 4 News research has identified a complete list of the weapons already at the rebels' disposal:
9K310 Igla-1, or SA-16 Gimlet
A Russian/Soviet infrared homing surface-to-air missile - used prominently in the Gulf War and also said to have been used in Rwanda and Bosnia
9K32 "Strela-2"- SA-7 Grail and AS-24
Soviet shoulder-fired surface-to-air missile with a highly explosive warhead and infrared homing guidance - the Strela has been used widely in nearly every regional conflict since 1968, including the Falklands War, Northern Ireland, Afghanistan and Iraq.
BM21 GRAD rocket launcher
A truck-mounted rocket launcher system, originally developed in Russia in the 1960s, with variants made by a wide range of countries including North Korea, China, Egypt, Iran and Hamas in the Gaza Strip. One battalion of eighteen launchers is able to deliver 720 rockets in a single volley.
Katyusha multiple launch rocket system
A rocket launcher system, which can be mounted on vehicles, originally developed by the Soviet Union for use in the Second World War. They were allegedly used in the Six Days War, the 2006 Lebanon War, the Soviet-Afghan War and the 1990 invasion of Rwanda by the Rwandan Patriotic Front.
9K11 Malyutka or AT-3 Sagger
A guided anti-tank missile system, developed in the Soviet Union, which can be fired from a portable suitcase launcher. The system was reported to have been used in the Vietnam War, the Yom Kippur War and the 2011 Libyan civil war.
An anti-tank missile system, which can be transported in compact packs. It was reportedly used by Hezbollah fighters during the 2006 Lebanon War.
Anti tank RPG-29 AND SPG-9
Other weapons at the rebels disposal range from rifles to anti-aircraft weapons: