THE first direct US strike on Syrian government forces escalates Western involvement in a terrible war. Worse, it plays straight into the hands of the Isis death cult.

Within hours of the Tomahawk missiles thudding into Syria’s Shayrat air base the genocidal group had launched another offensive in the area.

This was of no concern to the back-seat bombers in the House of Commons, as the Tories and their useful idiots on the Labour back benches lined up to salute Donald Trump for his killing spree.

Number 10 calls this illegal act of aggression a “proportionate” response to the horrific chemical weapons attack on Khan Sheikhoun.

There are a number of dangerous assumptions in this stance. For one, the notion that the United States has some sort of right to act as judge, jury and executioner when it comes to crimes committed on other countries’ territory.

That an appalling attack on civilians occurred in Khan Sheikhoun is beyond doubt, but Britain should be backing calls for an independent investigation into who was responsible.

One does not need to be an apologist for the Assad regime or its Russian backers to note that all sides in the Syrian civil war have fought with great brutality, and that the government’s opponents have proved themselves quite capable of murdering civilians on a regular basis.

That is as true of Ahrar as-Sham, which publicly welcomed the US air strikes yesterday, as it is of Isis or al-Qaida.

While Western governments pretend to support “moderate” rebels in Syria, the truth is that coalitions such as Ahrar as-Sham or Nour el-Din el-Zinki which have received Western backing and arms are also bent on establishing a theocratic state based on sharia law, have committed well documented atrocities against civilians including children and not infrequently fight in tandem with forces the US admits are terrorists such as the al-Qaida-affiliated Nusra Front.

The rebels are also known to have access to chemical weapons. In 2013, the Turkish authorities — no friends of Assad — found sarin gas canisters in the homes of suspected Islamists, and questions were asked in the Turkish parliament about the release of individuals arrested for possession of chemical weapons who were allowed to cross the Syrian border.

The Kurdish People’s Protection Units (YPG) have also reported the use of chemical weapons by Syrian insurgents against their troops.

For all gung-ho MPs like to talk about how Assad got away with a chemical weapons attack in 2013, it was never established that government forces were behind the attacks in Ghouta, while UN human rights investigator Carla del Ponte found there was little doubt the rebels had deployed sarin gas.

This is not to say that there is no possibility the Syrian government committed a war crime in Khan Sheikhoun, but it demonstrates that there are a number of other forces which could be responsible — and which, unlike Damascus, have much to gain from provoking greater US intervention in the war.

It has been evident for months that the “Islamic revolution” in Syria is being defeated. The government, with help from Russia, Iran and the Lebanese Hezbollah movement, has been steadily gaining ground against the rebels on most fronts.

Any bid by the United States to intervene against the government is likely to embolden the insurgents. It reduces the chance of success in stalled peace talks and risks prolonging the war.

The US says the strike was a one-off. We must hope so.

But Trump is not known for his caution. Socialists must be ready to resist any lurch into an inglorious war in Syria, in which our forces would be fighting alongside some of the most murderous religious extremists the world has known.