On Trump’s talks about nuclear testing, and the USA seeking to resume nuclear testing on a like for like basis with Russia and China:

Believe it or not, this doesn’t come solely from Trump. The State Department and Defence Intelligence Agency in the USA have indirectly accused China, and directly accused Russia, of carrying out covert supercritical nuclear tests that produce yield in violation of the CTBT for years.

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) which is signed but not ratified in 1996 by all three nations (USA - Russia - China), has the following obligations:

-Each State Party undertakes not to carry out any nuclear weapon test explosion or any other nuclear explosion, and to prohibit and prevent any such nuclear explosion at any place under its jurisdiction or control.

-Each State Party undertakes, furthermore, to refrain from causing, encouraging, or in any way participating in the carrying out of any nuclear weapon test explosion or any other nuclear explosion.

However the CTBT still allows for tests that produce zero yield/no explosion, known as subcritical tests. The US has carried out such tests since 1996 and publicised them, the last in 2020. However Russia revoked it’s ratification of the CTBT according to Putin, in November of 2023. In April of 2020 the US State Department made the following allegations in its annual compliance report, direct PDF link to US government website towards Russia and China, in the context of violating the CTBT:

RUSSIAN FEDERATION (RUSSIA) FINDING:

The United States finds that, since declaring its testing moratorium, Russia has conducted nuclear weapons experiments that have created nuclear yield and are not consistent with the U.S “zero-yield” standard.

CONDUCT GIVING RiSE TO ADHERENCE CONCERNS The United States assesses that Russia has conducted nuclear weapons-related experiments that have created nuclear yield since renewing its nuclear testing moratorium in 1996. Despite Russia renewing its nuclear testing moratorium in 1996, some of its activities since 1996 have demonstrated a failure to adhere to the U.S. “zero-yield” standard, which would prohibit supereritical tests.

PEOPLE’S REPUBLIC OF CHINA (CHINA) FINDING

In recent years, China continued work at its Lop Nur nuclear weapons test site. China’s possible preparation to operate its Lop Nur test site year-round and lack of transparency on its nuclear testing activities have raised concerns regarding its adherence to the U.S. “zero yield” nuclear weapons testing moratorium adhered to by the United States, United Kingdom, and France.

CONDUCT GIVING RISE TO ADHERENCE CONCERNS

In recent years, China’s possible preparation to operate its Lop Nur test site year-round and lack of transparency on its nuclear testing activities have raised concerns regarding its adherence to the U.S. “zero yield” standard adhered to by the United States, the United Kingdom, and France in their respective nuclear weapons testing moratoria. China continued work at its Lop Nur nuclear weapons test site throughout 2020

This would explain comments by Trump that Russia and China are testing nuclear weapons. He’s receiving intelligence reports that say so. Parts of these reports are public, such as the ones quoted above. Covert low yield (but not zero yield) underground tests that evade monitoring for the CTBT. The US, with Trump’s statements, is loudly and publicly accusing Russia and China of violating the CTBT, and saying that they will do so themselves.

If the CTBT is kaput, we go back to the Threshold Test Ban Treaty (TTBT) between Russia and the USA, which allows underground nuclear tests of a yield up to 150kt. However China is the big outlier, they are not part of such bilateral cold war treaties.