JERUSALEM: The Golan Heights will remain Israeli, Prime Minister Benjamin Netanyahu's office said Tuesday, after the US's top diplomat suggested American support for Israeli control of the plateau was not unshakeable.

"The Golan is very important to Israel's security" but "legal questions are something else," US Secretary of State Antony Blinken told CNN on Monday.

"As long as Assad is in power in Syria, as long as Iran is present in Syria... these pose a significant security threat to Israel... the control of the Golan in that situation I think remains of real importance to Israel's security," he said.

In response on Tuesday, a source in Netanyahu's office said: "Israel's position is clear. In any future possible scenario the Golan will remain Israeli."

Former US president Donald Trump signed a decree in March 2019 recognising Israel's sovereignty over the occupied part of the Syrian Golan, annexed in 1981 in a move never recognised by the international community.

Syria described Trump's decision at the time as a "flagrant violation" of its sovereignty.

Israel and Syria, which are still technically at war, are separated by a de facto border at the Golan Heights, which Israel has occupied since the end of the 1967 Six-Day War.