In the span of just a few short hours, two unprecedented developments occurred in the Syrian civil war on Sunday. One: A U.S. warplane shot down a Syrian air force jet after it struck positions of American-supported rebels. Two: Iran fired medium-range ground-to-ground missiles, ostensibly at Islamic State targets in Syria, in response to ISIS’ double terror attack in Tehran last week.

>> UPDATE: Iran's Missile Attack on Syria Failed: 5 Missed, 3 Landed in Iraq

The war in Syria, which has now lasted longer than World War II, continues to metamorphose. The only thing that stays the same is that Syria remains an arena for regional and world powers fighting over status, image and influence.

Video footage purports to show impact of Iranian missile strike in Syria.

Just two years ago, the regime of Syria's President Bashar Assad was tottering on the brink. His rule was saved by a Russian military intervention. Retaking Aleppo last December also enabled Assad to gradually regain control over other areas. (Though it seems that later on, a sticking point arose between Damascus and Moscow. Assad wanted more Russian help in order to advance faster, but Putin did not oblige.)

Two other processes are also happening at the same time: After a long delay, an international coalition began attacking Raqqa, the capital of ISIS' declared caliphate in northeast Syria; and Iran took advantage of the militant group’s retreat and entrenchment in Mosul to try to unite areas controlled by Shi'ite militias in west Iraq with areas controlled by Assad in east Syria.

However, Sunni organizations trained and financed by the United States are sitting in the middle, on the Iraqi-Syrian border, and they’re in Iran’s crosshairs. That is why there have been so many clashes in recent weeks in the vicinity of al-Tanf in southeast Syria.

The incident involving the downed Syrian fighter jet happened by the border, but closer to Raqqa. As far as the Americans are concerned, while they’re busy fighting against the Islamic State, Assad – who should also have an interest in defeating ISIS – is taking advantage of the opportunity to snipe at rebel organizations that the U.S. supports.

The Iranian missile fire on ISIS should be seen as a demonstration of power, a signal by Tehran to the Americans, Russians and also the Israelis that Iran is prepared to escalate the gamble in Syria in order to protect what it has already invested in defending its strategic interests there: support for Assad and establishing its influence in Iraq, Syria and Lebanon.

Open gallery view Iran missile launch: Map of region

Now the U.S. has also become caught up in this tension, without precision planning and perhaps without giving it enough thought. The Trump administration has no policy for Syria beyond being prepared to act more assertively than Obama did when America’s might is challenged. Thus, Trump approved the Cruise missile attack on a Syrian air base two months ago, after Assad used chemical weapons in Idlib province, and Americans shot down a Syrian jet on Sunday. Trump seems not to know or care about the details. Last week he relegated the responsibility for another arena, Afghanistan, to the Pentagon, which now gets to decide how many troops are needed to strengthen the forces there.

Americans are always worried about mission creep, as happened in Vietnam in the 1960s. The concern is that tactical decisions, mainly made to defend specific interests here and there, will ultimately bog America down in a major war that it doesn’t want. With Trump, this is a real possibility.

As in the previous years of the Syrian civil war, Israel is not getting directly involved, but important things are happening closer to home. Assad's regime is concentrating a lot of forces on attacking the town of Daraa in southern Syria, by the Jordanian border. Israel worries that in time, Assad’s forces could turn west toward the Syrian Golan, which in recent years has been controlled mainly by Sunni rebel groups. Israel has already warned that this is a red line, and says it will act to stop Hezbollah and the Iranian Revolutionary Guard from joining Assad's forces on the border.

On Sunday the Wall Street Journal reported that Israel has been broadly supporting local militias near the Golan border, paying salaries and aiding with arms and ammunition. The stated purpose is to establish a buffer that keeps the Assad regime and its supporters away from the border. Israel has always called the aid to the rebels humanitarian and says it amounts to supplying drugs, food and clothing to residents, and in giving medical care to the wounded and sick. But Jerusalem hasn’t bothered to deny the new reports, which could indicate that the gamble at stake, not only on the Syrian-Iraqi border but in the Golan too, continues to increase.