The following editorial was written before the launching of the U.S. missile attack on Syrian military targets. We join the nation in our hope for the success of the mission in discouraging the future use by the Syrian military of chemical and other internationally banned weapons.

All should share President Donald Trump’s outrage over the use of chemical weapons by Syrian forces against civilians in the rebel-held province of Idlib.

“When you kill innocent children,” the president said, “little babies, with a chemical gas that is so lethal, that crosses many, many lines.”

Yet the president needs to be considered and calculated in his response and should seek support and collaboration with allies. Any action by U.S. military forces can invite a reaction. The Trump administration has to carefully consider what those reactions may be and what implications they carry.

The situation is highly complicated, in particular because of the military alliance between Russia and Syrian President Bashar Assad. A misstep could bring U.S. forces into direct conflict with their Russian counterparts. And the civil war in Syria is being waged within the context of a larger sectarian struggle between Islamic Sunni and Shiite factions.

Also of concern is the inconsistency coming from the Trump White House. It was only a week ago that Nikki Haley, the U.S. ambassador to the United Nations, declared that the Trump administration does not consider it a priority that Assad be removed from power. The president repeatedly has suggested a potential alliance with Russia in opposition to the Islamic State.

It is not as if the chemical attacks were some great departure for the Assad regime. Many “little babies,” along with entire families, were killed in the unrelenting attacks by Syrian and Russian warplanes on Aleppo. They did not die in chemical attacks, perhaps, but by barrel bombs and internationally banned cluster munitions in attacks targeting residential buildings, hospitals, medical clinics and schools.

In December, leaflets dropped by Syrian and Russian aircraft made the intent of the attackers clear.

“If you do not leave these areas urgently, you will be annihilated,” the leaflets said. “You know that everyone has given up on you. They left you alone to face your doom, and nobody will give you any help.”

In fact, there was no place to flee. Those final attacks brought the death total in Aleppo since 2011 to about 400,000, according to United Nations estimates. Scores more were injured in the attacks or became refugees.

With the Trump administration saying in the wake of such carnage that Assad’s removal was not a priority, and Russia a potential ally in the war on the Islamic State, it may be little wonder that the Syrian tyrant felt emboldened to turn to chemical weapons again.

Turkey officials treating victims identified the killing agent as sarin gas. The death toll is unclear, but it appears to exceed 100, with hundreds more sickened by the attack.

As the president repeatedly reminds us, his administration inherited a Syrian mess badly managed by his predecessor. President Barack Obama warned of a red line that Assad could not cross, but failed to respond militarily when Assad crossed the line with chemical attacks. At that time, allies appeared willing to assist. Instead, Obama approved a deal with Russia to remove Assad’s chemical stockpile. Clearly Russia did not get it all. That’s hardly surprising.

However things got to this point, the problem is now Trump’s. He has plenty of generals in his administration, but it is weak in diplomatic experience, and diplomacy must play a factor in any response. Haley is new to her role. Many top positions in the State Department remain vacant. Secretary of State Rex Tillerson is a former oil executive familiar with striking international business deals but not with the nuances and conflicting priorities inherent in high-level foreign policy. His recent comments during a visit to Turkey, that “the longer-term status of President Assad will be decided by the Syrian people,” were downright bizarre given the reality on the ground.

At some point a new president faces a crisis. It has arrived for Trump. Dealing with a growingly belligerent nuclear-armed North Korea may not be far behind. How the president reacts could have grave and lasting implications. He must act deliberately and not impulsively.

In other words, Trump must go against his nature.