The first half resolves based on the US president after inauguration day 2025.
The second half resolves based on the actions of the US president during their four year term of office (2025-2029).
An attempt to leave includes any attempt to send a notice of denunciation under article 13, regardless of whether it is found to be legally valid, and regardless of whether the one year waiting period expires. It also includes attempts to leave without invoking that article, such as invoking a fundamental change or circumstances, a material breach, domestic law, annulment, etc. It includes any actions of the executive branch of government, plus any actions of the legislative or judicial branch that are at the direction of the US President.
https://en.wikipedia.org/wiki/Withdrawal_from_NATO