(CNN) — The United States will not participate in an international effort to develop and distribute a coronavirus vaccine because the initiative is tied to the World Health Organization, the White House said Tuesday.

The decision, which comes at a critical point in the US coronavirus response, with cases topping 6 million, will keep the US isolated from the more 170 countries involved in the COVAX initiative working to provide worldwide access to an effective vaccine.

“The United States will continue to engage our international partners to ensure we defeat this virus, but we will not be constrained by multilateral organizations influenced by the corrupt World Health Organization and China,” White House spokesperson Judd Deere said in a statement.

“This President will spare no expense to ensure that any new vaccine maintains our own FDA’s gold standard for safety and efficacy, is thoroughly tested, and saves lives.”

Aside from underscoring Trump’s long-standing distrust of global alliances and, in particular, his criticism of the WHO, the decision marks a notable bet on Operation Warp Speed, the federal government’s effort to speed development of drugs, vaccines and other measures to fight the pandemic. Two Covid-19 vaccines are in Phase 3 trials in the US — those made by Moderna and Pfizer/BioNTech — and two more are expected to begin Phase 3 trials by mid-September.

“Under President Trump’s leadership, vaccine and therapeutic research, development, and trials have advanced at unprecedented speed to deliver groundbreaking, effective medicines driven by data and safety and not held back by government red tape,” Deere said.

Trump, who has long eschewed global alliances and institutions, has increasingly blamed others, including China and the WHO, amid scrutiny of his own administration’s response to the pandemic.

In July, the Trump administration notified Congress and the United Nations that the US is formally withdrawing from the WHO, multiple officials told CNN.

The withdrawal, which goes into effect next July, has drawn criticism from bipartisan lawmakers, medical associations, advocacy organizations and allies abroad. Democratic presidential nominee Joe Biden previously vowed to reverse the decision “on (his) first day” if elected.

Critics have questioned whether the WHO is independent enough, given China’s rising wealth and power. They point to the WHO’s effusive praise of China’s response to the coronavirus pandemic. Agency officials have defended their early actions when it came to fighting the coronavirus, noting that much was unknown about the virus back in January.

The-CNN-Wire™ & © 2020 Cable News Network, Inc., a WarnerMedia Company. All rights reserved.