On March 4, Russian dissident Sergei Skripal and his daughter, Yulia, suffered from a nerve agent attack. The father and daughter are living in London.
The US, the UK, France, and Germany all blamed Russia for the attack.
Although Trump initially failed to deliver a forceful condemnation of Russia for the attack, other officials in his administration picked up the slack.
"Over the past four years, Russia has engaged in a campaign of coercion and violence, targeting anyone opposed to its attempted annexation," State Department spokeswoman Heather Nauert said in a statement.
"We stand behind those courageous individuals who continue to speak out about these abuses and we call on Russia to cease its attempts to quell fundamental freedoms of expression, peaceful assembly and association, and religion or belief."
Secretary of State Rex Tillerson said the attack "clearly came from Russia" and US Ambassador to the US Nikki Haley said the US stood in "absolute solidarity" with the UK after the attack.
A full day after the UK blamed Russia, Trump told reporters that "as soon as we get the facts straight, if we agree with them, we will condemn Russia or whoever it may be." Referring to the UK's findings, he added, "It sounds to me like they believe it was Russia, and I would certainly take that finding as fact."
National-security experts were baffled and alarmed by Trump's delayed reaction to the chemical attack.
Trump then joined a statement with UK Prime Minister Theresa May, French President Emmanuel Macron, and German Chancellor Angela Merkel agreeing that there was "no plausible alternative explanation" than that Russia was to blame for the attack.