Do you honestly think the US would openly tell their competitors that they are almost out of Patriot missiles? That would be like Ukraine and Russia being honest about the number of troops killed. 
Honestly, governments often try to keep weapon stocks as secret as possible, I concede that. However you have to look into it as much as possible, what data and info is available and then decide. The US keeps tabs on other countries' weapons stocks constantly and have estimates, they may not know exactly but approximately. In the US I understand weapons manufacturing is by private companies, which the government then pays them for (and apparently is why they cost more to manufacture in the US) and they have public records of what their targets are for the year and future years for different weapons. The manufacturing sites locations and workforce numbers are public. I understand that in other countries the government owns the companies and factories and so on. But take the Patriot missiles for example, if the stocks were plentiful the US would gladly sell as many of them as they possibly could, because that's the goal of the MIC right? They wouldn't have to ask other NATO countries, or even non-NATO countries, to send their Patriots to Israel or Ukraine, whatever the case may be, don't you think? The US has asked other countries to please let Ukraine have the Patriots they have already ordered and been promised, to wait longer. Ukraine is begging the US for Patriots and other weapons constantly, and they would buy them from the US with other NATO countries' monies but it's just not happening. The US would gladly take that money. Unless you know otherwise?
It appears the US has had to tell the whole world of the situation with the shortages, China and other countries are obviously watching. In fact some Chinese politician has recently said that they prefer the US keeps the Ukraine-Russia conflict going as long as possible because the US is depleting its stock and can't 'pivot to Asia' while this situation is ongoing, and Trump and his admin has said numerous times they would like the conflict to end because they need to pivot. Israel too needs more US weapons and the Iran conflict had to temporarily pause because Israel was out of US weapons, the air-defense missiles primarily. The importance of weapons support in US policy is said to be as follows: Taiwan first, Israel second and then Ukraine. I was a bit surprised that Israel wasn't first.
