Historical context: The United States has a long history of conducting unethical medical experiments on vulnerable populations, both domestically and internationally.

* For example, the infamous Tuskegee Syphilis Study, which ran for four decades until 1972, withheld treatment from African-American men with syphilis in order to study the progression of the disease.

* Similarly, the US military conducted radiation experiments on unsuspecting soldiers and civilians during the Cold War, exposing them to dangerous levels of radiation without their knowledge or consent.

Power dynamics: The Philippines has been a close ally of the United States for decades, and the US military has a significant presence in the country.

* This power imbalance can create an environment where the US military feels it can act with impunity, disregarding the ethical and legal rights of Filipino citizens.

Lack of transparency: The US military has a track record of operating in secrecy, often without proper oversight or accountability.

* This can make it difficult to discover and investigate unethical activities, such as the secret anti-vax campaign in the Philippines.

Researcher's expertise: The researcher cited in the article is likely to be an expert in the field of medical ethics or public health, with a particular focus on the history of unethical medical experiments and the power dynamics between powerful institutions and vulnerable populations.

* Their expertise would give them a deeper understanding of the factors that can lead to unethical behavior and why it's important to bring such activities to light.