Tuesday’s strike marks an intensification of U.S. military action against the Assad regime, whose human rights violations have sparked mounting concern from the Trump administration. On April 26, the U.S. launched more than 50 tomahawk missiles into Syria, targeting the site of a recent chemical-weapons attack. The strike was the nation’s first military operation against an Arab government since 2011, when President Obama sanctioned a military intervention in Libya. At the time of the missile strike, Trump said the move was vital to national security.

Since then, U.S. involvement in the Syrian war has continued to escalate. On May 18, U.S.-led coalition jets carried out a strike that closely paralleled Tuesday’s attack. Following the incident, CBS News reported that pro-regime forces twice violated the deconfliction zone in al-Tanf—once when more than a dozen regime vehicles infringed on the radius of the U.S. army convoy, and again when an unarmed fighter-bomber entered the zone.

In recent months, Russia, which is allied with Assad, has been less than pleased with increased U.S. military aggression in the region. Dmitry Peskov, the spokesperson for Russian President Vladimir Putin, referred to April’s missile strikes as a “violation of international law,” adding that the strikes “will inflict major damage on U.S.-Russia ties.” According to RT, a member of the Russian parliament shared a similar response in the wake of Tuesday’s attack, calling the strike “an act of aggression” and “a step by the U.S. towards engaging in an open conflict in Syria.” A day earlier, U.S.-backed Syrian Democratic Forces (SDF) launched an operation to capture Raqqa, an ISIS stronghold in Syria. The Trump administration announced in May that it would arm and train Syrian Kurdish forces—a critical move in the Raqqa offensive, but one that could have damaging consequences for U.S.-Turkey relations.

While defeating ISIS has long been a priority for the Trump administration, targeting the Assad regime is a more recent development. Trump previously told The New York Times that “fighting Assad and ISIS simultaneously was madness, and idiocy.” Meanwhile, the U.S. Defense Department claims their actions in al-Tanf are consistent with previous policy. “Now that [Syrian and allied forces have] backed off, we’re not going after them,” Eric Pahon, a spokesperson for the department, told Bloomberg in May. Still, he said, given the nature of the war, “anything can happen.”

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