To wit, an American fighter shot down a Syrian warplane on Sunday, “the first time the American military has downed a Syrian aircraft since the start of the civil war in 2011.” Observers immediately called the incident a marked escalation in the conflict.

And their view was quickly vindicated: “Russia on Monday condemned the American military’s downing of a Syrian warplane, suspending the use of a military hotline that Washington and Moscow have used to avoid collisions in Syrian airspace and threatening to target aircraft flown by the United States and its allies over Syria.”

Those skeptical of U.S. intervention in the Syrian civil war have long warned that it could escalate into a civilization-warping conflict between nuclear powers. But neither Vietnam nor Afghanistan nor Iraq nor Libya has persuaded today’s hawks to sufficiently weight the unintended consequences that plague all complex military interventions. And there are so many varieties of hawks that are urging action.

The complexity of the civil war in Syria is underscored by the fact that the ascendant pro-war faction inside the Trump administration is composed of Iran hawks. According to reporters Kate Brannen, Dan De Luce and Paul McLeary at Just Security, antagonism toward Iran is causing two officials in the Trump White House to push for broadening the conflict, against the advice of officials at the Pentagon:

Ezra Cohen-Watnick, the senior director for intelligence on the National Security Council, and Derek Harvey, the NSC’s top Middle East advisor, want the United States to start going on the offensive in southern Syria … Their plans are making even traditional Iran hawks nervous, including Defense Secretary James Mattis, who has personally shot down their proposals more than once, the two sources said … Despite the more aggressive stance pushed by some White House officials, Mattis, military commanders and top U.S. diplomats all oppose opening up a broader front against Iran and its proxies in southeastern Syria, viewing it as a risky move that could draw the United States into a dangerous confrontation with Iran, defense officials said. Such a clash could trigger retaliation against U.S. troops deployed in Iraq and Syria, where Tehran has armed thousands of Shiite militia fighters and deployed hundreds of Revolutionary Guard officers.

Put another way, Iran hawks in the Trump White House want to broaden the conflict there in a manner that pits the U.S. against another country that also seeks the defeat of ISIS, the ostensible reason the U.S. is involved in Syria in the first place.

Meanwhile, hawks in Iran are escalating that country’s role in Syria: “Iran announced Sunday the Iran Revolutionary Guards had launched ballistic missile strikes on Saturday against ISIS targets in Syria, dramatically escalating the country’s role in the Syrian conflict. The mid-range ground-to-ground missiles targeted militants in eastern Syria in retaliation for the deadly terrorist attacks in Tehran earlier this month.”