President Joe Biden raised concerns Wednesday over the potential of Russian forces to use chemical weapons in Ukraine.

Biden brushed off most questions from reporters while departing the White House for Brussels but told reporters, "I think there's a real threat," when asked what the likelihood for "chemical warfare" in Ukraine really is.

Biden will meet with other NATO and European leaders in Brussels on Thursday before traveling to Poland for bilateral meetings with President Andrzej Duda.

Senior Biden administration officials, including White House press secretary Jen Psaki, have warned for weeks about Russian efforts to stage a false flag chemical attack as a pretext for escalating its war actions in Ukraine.

"Now that Russia has made these false claims," Psaki tweeted on March 9, "we should all be on the lookout for Russia to possibly use chemical or biological weapons in Ukraine, or to create a false flag operation using them. It’s a clear pattern."

"Russia is the country that has a chemical and biological weapons program. So, the objective was to make clear the inaccuracy of the information, the misinformation they're trying to put out, and make clear to the world that they not only have the capacity, they have a history of using chemical and biological weapons, and that, in this moment, we should have our eyes open for that possibility," she added in a White House briefing the following day.