US President Donald Trump's decision to strike a Syrian government base in retaliation for what he said was a chemical attack comes four years after his predecessor, Barack Obama, faced a similar challenge in Syria - and chose to back down.
A suspected poison gas attack on Tuesday in the rebel-held town of Khan Sheikhoun in Syria's Idlib province killed at least 86 people, including 27 children.
However, when Obama had vowed that the use of such weapons would "change my calculus" to justify military intervention in Syria, Trump repeatedly took to Twitter to heavily criticise him - and called him a "foolish leader".
Here is a selection of tweets by Trump about US intervention in Syria before he became president.
Source: Al Jazeera and news agencies