The hundreds of thousands who have taken to the streets of Britain over the past month in support of and solidarity with the people of Gaza have seen their protests denounced by neocons and rightwingers because they aren’t about some other group of people, somewhere else.

The “why don’t they march against something else” crowd accuse us of silence on those atrocities. There are certainly many terrible humanitarian disasters in the world, most recently that of the Yazidis in Iraq, about which we must all feel anguish. Our argument is that our government and the US’s past intervention have not helped the people of the Middle East, but made things worse. The point of a mass demonstration is to put pressure on our government and to alter public opinion in this country. They have had an impact. Public opinion remains strongly anti-intervention and anti-war, and last year, mobilised public opinion was instrumental in stopping David Cameron’s attempt to bomb Syria.

Last Saturday’s demonstration was the biggest ever pro-Palestine protest at 150,000. There have been thousands of smaller actions around the country. There is widespread outrage at Israel’s brutal assault on Gaza and a determination to end the siege which is causing such misery to Gazans.

Why do people feel strongly enough to take to the streets over Gaza but not over other issues? Partly because there is a deep and longstanding movement in solidarity with the Palestinians that encompasses trade unions, community groups, faith groups and activists. But it is also partly because our government is seen as complicit in Israel’s oppression of Palestinians. We provide arms, we trade with Israel and we defend the actions of the government there, just as we did in 2008-09 and 2012 when Gaza was bombed.

Our former prime minister and absurdly named envoy for peace in the Middle East, Tony Blair, supports Israel’s foreign policy. David Cameron, according to Sayeeda Warsi, instructed his ministers not to say Israel’s bombing might be disproportionate, and blames the conflict on Hamas although it long predates Hamas’s existence. While sanctions are applied to Russia over the Malaysia Airlines flight MH17 disaster, no sanctions are imposed on Israel.

Contrast this with Cameron’s support for intervention elsewhere and look at the consequences of those interventions. Libya, hailed as a huge success by Cameron three years ago, is now so riven by war that embassies have closed and British nationals evacuated by the Royal Navy. The arming of the Syrian rebels by western and Middle East powers, especially Turkey and Saudi Arabia, has produced blowback on a spectacular scale as Islamic State (Isis) sets up its bloody caliphate across hundreds of miles of Iraq and Syria, with disastrous consequences.

The terrible plight of the Yazidis, trapped by Isis and fearing a terrible fate if captured, is heart-rending but will not be helped by further military intervention in Iraq. The occupation of Iraq broke the infrastructure of Iraqi society. Sectarian tensions were encouraged and exacerbated by the occupying forces, and some of those now supporting Isis formed the opposition to this occupation.

Many people know that UK government foreign policy, far from solving problems, causes more humanitarian disaster. In a democracy, anyone is of course entitled to demonstrate over a range of issues. So maybe those Tory bloggers, shock jocks and neocons who are such warriors on social media should head down to Hyde Park and see how many they get around them for more military intervention.