The <a href="https://www.cfr.org/in-brief/quad-indo-pacific-what-know" target="_blank">Quad</a> countries are the US, India, Japan, and Australia. Tensions <a href="https://www.voanews.com/a/china-japan-officials-meet-amid-taiwan-tensions-/6706508.html" target="_blank">continue</a> in the South China Sea and <a href="https://economictimes.indiatimes.com/news/defence/china-threatens-bangladesh-says-ties-will-be-hit-if-it-joins-quad/articleshow/82544639.cms" target="_blank">elsewhere</a>, with increasing fears of some form of military <a href="https://www.cnn.com/2022/05/23/asia/the-quad-tokyo-summit-explainer-intl-hnk/index.html" target="_blank">confrontation</a>. For the purposes of this question, drones may be considered part of "forces" if so claimed by the accusing party's forces. Accusations of "warning shots" being fired would count. An accusation of a vessel or aircraft deliberately ramming another would count, but accidental collisions would not. Cyberattacks and the use of directed-energy weapons (e.g., microwaves, sonic weapons) would not count. An accusation by one Quad country against another Quad country would not count, and both the accused use and the accusation must occur during the question's open period to count.