The remarks by the former generals come in the wake of China and Russia vetoing further sanctions against North Korea last month for the first time since 2006.
The Russian Embassy in the U.S. took aim at a Newsweek op-ed which said that Moscow could use weapons of mass destruction in Ukraine.
Yuriy Bova, mayor of the Ukrainian city Trostianets, said officials found traces of sarin and other chemical substances.
Ukraine's defense intelligence department wrote that Russia's plan is to stage attacks on its own territories and divert the blame onto Ukraine.
Trump ordered multiple airstrikes when chemical weapons were used in Syria in 2017.
"We cannot allow chemical weapons, or God forbid, tactical nuclear weapons, to be the next rung in the escalation ladder that we allow Putin to go to," Congressman Michael Waltz said.
"All options are on the table," UK Armed Forces minister said.
The Azov Regiment, a unit of the National Guard of Ukraine, said chemicals were of an "unknown origin" and dropped via an unmanned aerial vehicle in Mariupol.
"He's already used chemical weapons in the past," U.S. President Joe Biden said regarding Russian President Vladimir Putin on Monday.
"We've been clear, if they escalate to this level, we will respond aggressively to what they are doing," U.S. Ambassador to the U.N. Linda Thomas-Greenfield warned.
National security adviser Jake Sullivan's warning came as Russia has been spreading a conspiracy theory that the U.S. funds biological weapons labs in Ukraine.
Scientists and the State Department have challenged the Kremlin's suggestion that the United States is financing the development of chemical and biological weapons in Ukraine.
A spokesperson for China's Foreign Ministry said Russia "has uncovered the secret of the U.S. labs in Ukraine."
NATO countries have refused Ukrainian President Volodymyr Zelensky's calls for a no-fly zone over Ukraine, fearing it could risk provoking a widespread war.
White House press secretary Jen Psaki tweeted that Russia's claims of U.S. bioweapons in Ukraine could be an excuse for Russia to release one of its own.
U.S. says Russian allegations of possible chemical attack by American mercenaries in Donbas are "completely false."
The head of the international chemical weapons watchdog reported that out of 77 allegations against Syria making or using chemical weapons, 17 of those cases were likely. Russia claimed factual and technical errors and acting under pressure from Western nations.
"I worry that we're entering a time where anti-democracy forces will see value in developing new kinds of chemical weapons, and—noting the disruptive impact of COVID-19—perhaps biological weapons."
"Someone had launched a major chemical weapons attack on the suburbs, no more than 5 miles from his hotel. They had killed and injured scores of civilians, and perhaps more...And it happened at the precise moment when a body of U.N. experts was present in Syria to document the deed."
Dozens of protesters in Seattle and Portland are convinced that law enforcement officers exposing them to tear gas led to them having abnormal menstrual cycles.
Bestselling author Greg Mitchell debates Hudson Institute senior fellow Rebeccah Heinrichs.
Hong Kong's top health official has claimed that tear gas used by police on protesters poses no public health risk, days after police were reported to use the gas at a university campus. Some have expressed fears that the chemical weapon used in the city could contain the toxic pollutant dioxin.
Newsweek spoke to several chemical weapons experts on why the devastating substance continues to be used without international accountability.
"This very much looks like it was caused by white phosphorus," British chemical weapons expert Hamish de Bretton-Gordon told "The Times of London."
While the president criticized Russia and Iran during the Security Council meeting, he expressed appreciation for the "restraint" both nations have shown in Syria's Idlib province.
Bob Woodward's "Fear: Trump in the White House" will be released on September 11.
There have been hundreds of chemical attacks in Syria since 2011, but Bashar al-Assad continues to be protected by his Russian allies.