In an exclusive look at the preparations for the next war by a terrorist organization in Gaza, the BBC's Quentin Sommerville was allowed to film Islamic Jihad's tunnels and launch sites that it has rebuilt so as to be ready to attack Israel again in the near future.

In the video published late last week the British journalist reports that the terrorist organization has "rearmed and replenished their ranks" since Operation Protective Edge last summer.

He is told by one Islamic Jihad terrorist "whether it's under the ground or over the ground we are prepared for any aggression on the Gaza Strip."

After being blindfolded, Sommerville was taken to a concealed 120 millimeter mortar launcher buried under an olive grove in southern Gaza, supposedly right by the Israeli border.

The mortar shells proved among the most lethal weapons in the Gazan terrorist arsenal during the last operation, claiming numerous Israeli lives including that of a four-year-old boy in countless volleys on Israeli civilians.

Islamic Jihad showed the reporter how the mortar launcher site led deeper underground into a tunnel, which the terror group has busily been building after Israel destroyed many of the terror attack tunnels during the last war.

Speaking from the tunnel, Sommerville says of it "you can see how well constructed it is, it's an extensive network, and Palestinian Islamic Jihad say they used it in the last war and they're ready to use it in the next."

Hamas and Islamic Jihad have been using aid materials to rebuild their tunnels, with a massive smuggling ring recently revealed to have given Hamas military materials even in the midst of the last war.

The video also shows extensive Islamic Jihad training meant to prepare the terrorists for the next round of fighting.