President Trump responded on Twitter to the alleged chemical attack by Syrian government forces that left dozens dead, calling out Russian President Vladimir Putin by name for his backing of the Assad regime.

This tweet is important. So far, Trump has avoided at all costs saying anything negative or confrontational about Putin. Trump has let his administration take tough actions against Russia — like sanctions, sending lethal arms to Ukraine, expelling Russian diplomats — but his red line has been criticizing Putin. As we've reported previously, the president is loath to criticize Putin by name or call him out in one-on-one conversations.

The big picture: It's part of the Trump paradox. He still believes the United States and Russia have plenty of shared interests and wants to mend the relationship. He also thinks the only way to do this is by building a warm personal relationship with Putin, according t0 people who have discussed the issue privately with Trump. But this dual-track strategy — be nice personally and tough administratively — becomes more implausible every time Trump authorizes a harsh action against Russia and every time Putin authorizes a new abomination.

• We saw, with this tweet, Trump hit the limits of this strategy. 

More tweets from Trump on the attack:

Get more stories like this by signing up for Jonathan Swan's weekly political lookahead newsletter, Axios Sneak Peek.