Prime Minister Benjamin Netanyahu has affirmed that Israel is prepared to conduct military action inside Syria to keep “game-changing” weapons out of terrorists’ hands. In an interview with the BBC in London Wednesday, Netanyahu also warned of a possible backlash if the international community decides to arm rebel groups.

“The main areas of concern to us are the arms that are already in Syria — these are anti-aircraft weapons, these are chemical weapons and other very, very dangerous weapons that could be game-changers,” he said. “They will change the conditions, the balance of power in the Middle East. They could present a terrorist threat on a worldwide scale. It is definitely our interest to defend ourselves, but we also think it is in the interest of other countries.”

Netanyahu was in London to attend the funeral of Baroness Margaret Thatcher, whom he hailed as a “great leader,” and after the ceremony met with UK Prime Minister David Cameron at 10 Downing Street.

Israel has been training a wary eye on developments in Syria, and particularly on the Golan Heights, where the fighting has on several occasions spilled across the border in the form of stray mortar rounds and sporadic fire on Israeli soldiers. Last week, IDF troops fired a guided missile at a Syrian army post after shots from the position damaged an IDF vehicle. Earlier in the month, IDF tanks fired at a Syrian position after small arms fire was directed at Israel.

The prime minister warned of possible dangers should the international community begin to supply rebels with weapons in addition to training and the nonlethal equipment, such as vehicles and communications devices, that has already been deployed in the field. The concern, he said, was that terrorist-affiliated groups fighting against the Bashar Assad regime could put the weapons to other use.

The question is, “Which rebels and which weapons?” Netanyahu said.

The prime minister explained that Israel was not seeking a fight with Syria, but was resolved to safeguard its security. In the past he has made it clear that Israel will not allow chemical weapons to be transferred to terrorist groups, particularly Lebanon’s Hezbollah.

“We are not aggressive,” he said. “We don’t seek military confrontation, but we are prepared to defend ourselves if the need arises, and I think people know that what I say is both measured and serious.”

Netanyahu refused to answer questions about an alleged Israeli airstrike inside Syria in January that destroyed several vehicles thought to be transporting anti-aircraft weapons to Lebanon. According to some reports, that raid also inflicted severe damage on a Syrian chemical weapons facility. Israel has yet to officially confirm that it was behind the strike.