They are intentionally vague and don't get into details.

Ukraine Has No Biological Weapons Program...no other European state nor the United States possessed any biological weapon development programs, in compliance with their obligations under the BWC.

Here's just a few of the times the US has used biological agents and chemical weapons on innocent people and animals.

• In 1976, the US tested Agent White, a powerful pesticide developed by Dow Chemical, in Cherokee county, North Carolina. Within 3 years, the rate of cancer deaths leapt to 60% above the national average.
• In 2018 after the release of a suppressed ISC (International Scientific Commission) report, and the release of declassified CIA communications daily reports in 2020, it was revealed that the US used germ warfare in the Korean war, 2. Many of these attacks involved the dropping of insects or small mammals infected with viruses such as anthrax, plague, cholera, and encephalitis. After discovering evidence of germ warfare, China invited the ISC headed by famed British scientist Joseph Needham, to investigate, but the report was suppressed for over 70 years.
• US dropped large amounts of Agent Orange, an herbicide developed by monsanto and dow chemical for the department of defense, in vietnam. Its use, in particular the contaminant dioxin, causes multiple health problems, including cleft palate, mental disabilities, hernias, still births, poisoned breast milk, and extra fingers and toes, as well as destroying local species of plants and animals. The Red Cross of Vietnam estimates that up to 1 million people are disabled or have health problems due to Agent Orange.1, 2
• In 1950, the US Navy secretly infected over 800,000 residents of the San Fransisco Bay Area with Serratia marcescens, a human pathogen known to cause urinary and respiratory infections, during Operation Sea-Spray, in one of the largest human experiments in history. The residents of the area were not informed, making the event a serious violation of the Nuremberg Code on medical ethics. In the following month, 11 residents checked in at a local hospital with a rare urinary tract infection (one patient, Edward J. Nevin died as a result), and the area saw a spike in pneumonia cases. The military tested biological agents on US citizens in at least six other similar tests causing a variety of symptoms such as whooping cough throughout the 50s and 60s in Florida, the Midwest, New York, Washington, and Pennsylvania. 1
• In 1968, the US army tested VX gas, a nerve agent to be used in biological warfare, in the Skull valley Indian reservation in Utah. 27 miles away from the test, 6,000 sheep died, known as the Dugway sheep incident. Since its founding in 1941, much of the activity at Dugway Proving Ground has been a closely guarded secret. Activities at Dugway included aerial nerve agent testing.[2] According to reports from New Scientist, Dugway was still producing small quantities of non-infectious anthrax of a type used in the making of vaccines as late as 1998, 30 years after the United States renounced biological weapons.[3] There were at least 1,100 other chemical tests at Dugway during the time period of the Dugway sheep incident. In total, almost 500,000 lb (230,000 kg) of nerve agent were dispersed during open-air tests.[2] There were also tests at Dugway with other weapons of mass destruction, including 332 open-air tests of biological weapons, 74 dirty bomb tests, and eight furnace heatings of nuclear material under open air conditions to simulate the dispersal of fallout in the case of meltdown of aeronautic nuclear reactors.
• In 1981, in an act of biological warfare, the US released a strain of Dengue fever into Cuba, developed at Fort Dietrich. A total of 320k people were infected, 158 people died, including 101 children under the age of 15.
• In 1971, A CIA operative told a reporter he delivered a strain of the African Swine Fever virus from an army base in the Canal Zone to anti-Castro Cubans. An outbreak of the disease then occurred in Cuba, resulting in the slaughter of 500,000 pigs to prevent a nationwide animal epidemic. It was labeled the "most alarming event" of 1971 by the United Nations Food and Agricultural Organization.1

It is functionally identical, given the close recent history between the two countries. For that matter, all humans are close, especially at a population level. People are trying to make this too complicated. Conventional weapons are perfectly capable of doing massive damage to an army without insane amounts of collateral damage, both to civilians and allies.

The US doesnt care about sacrificing Ukrainians as long as they can hurt Russia.

Organizations like CIA have a long history of pursuing precisely these kinds of insane ideas.

These were bioweapons labs left over from USSR days, and US didn't take over these labs for any sort of altruistic purpose.