After seven years of murderous conflict, Syria is now the battlefield for a multitude of conflicts, some intertwined, some entirely unrelated and with their own logic, driven by a cast of regional and world powers each with their own agenda. The overnight airstrikes only serve to sharpen their rivalry. Here are the key players:

The Assad regime

Syrian president Bashar al-Assad is increasingly confident of his survival in office, shored up and propelled forward by his Russian and Iranian backers. His aim is to consolidate his position in the west of the country, eliminating the last pockets of resistance, and then expand his control eastwards. Use of chemical weapons appears to reflect a desire to achieve this at minimal cost by spreading terror. Denying Assad that weapon with airstrikes may slow him down but is unlikely to threaten his grip.

Syria: 'Mission accomplished,' says Trump after overnight strikes – live updates Read more

Russia

For Vladimir Putin, the struggle in Syria is emblematic of the central theme of his rule, the restoration of Russia as a great power, whose views and interests in the Middle East and beyond have to be taken into account. Helping the Assad regime to prevail is an all-or-nothing proposition, a test of strength with the west and the ground on which the spread of western-inspired regime change is finally repulsed. The airstrikes are a humiliation, especially after Russian officials threatened to shoot down incoming missiles and planes, but it is one that has to be swallowed. Putin is well aware of the dangers of head-on confrontation with the US and its allies.

Play Video 2:05 What you need to know about the Syria strikes – video report

Iran

Iran sees Syria as an essential buffer zone. The fall of Assad and the rise of a Sunni regime would be a strategic nightmare for them. But Tehran, and the Islamic Revolutionary Guards Corps, also see Syria as a bridge to Hezbollah, their client militia in Lebanon that has done much of the heavy fighting in Syria. That puts Tehran in a position to pose a serious threat against Israel, which serves as insurance from Israeli attack. Despite posturing from Tehran, it is not looking for a confrontation with the US, and as long as airstrikes are directed only at chemical facilities, it will let them pass without response.

Israel

Iran’s gain in Syria is very much Israel’s loss. Israel is determined to disrupt Iranian lines of communication, control and supply to Hezbollah and keep Iranian-run militias well back from the line of separation at the Israeli-occupied Golan Heights. It prefers the US and Russia to restrain the Iranians, but if necessary Israel is likely to plunge in to southern Syria to confront the Iranians and create a buffer zone. It will want to draw in the US on its side in a wider role than counter-proliferation and counter-terrorsim.

United States

The mantra of the Trump administration is that it is only in Syria to fight Isis. Policing the use of chemical weapons with airstrikes is portrayed as an exceptional responsibility, driven by a national interest in non-proliferation. Trump has cut off the Obama policy of half-hearted and intermittent backing for rebel groups seen as moderate. But the Trump White House is also drawn by the desire to contain Iran, and that may yet pull the US deeper still into the battlefield. That is something that defence secretary James Mattis resisted in the latest wave of airstrikes but he may not prevail in the future.

United Kingdom

The UK sees its role as a partner in the anti-Isis coalition and sees its participation in strikes as an international non-proliferation responsibility, and part of the price of being a permanent member of the UN security council. London is also highly aware that the refusal to take part in planned punitive strikes in 2013 after an earlier chemical weapons attack weakened its relationship with Washington.

France

Emmanuel Macron has taken a particularly strong line on punishing chemical weapons use, and like the UK, France sees participation in such strikes as part of the burden of retaining its major power status, by policing non-proliferation norms. Paris also sees the anti-Isis fight as being a national security imperative, given that it has been one of Isis’s principal targets.

Turkey

Recep Tayyip Erdogan was initially one of the most vociferous advocates of regime change in Damascus, but now finds himself seeking accommodation with the regime and its backers to break up the Kurdish hold of the territory along the Turkish-Syrian border. His expeditionary “Olive Branch” incursion into Kurdish held territory, however, risks confrontation with the Americans, who see the Kurds as their most effective partner against Isis.