

During my long cooperation with the United States armed forces, I have witnessed respective times the situation of stopping aid to countries supported by the United States.. This has always been done in advance for the reorganisation of the retention strategy developed for this purpose, the provision and distribution of combat, material and method resources covered by the assistance.
It besides gave time to the beneficiary country to get another sources of supply. Stopping supplies immediately and the "lockdown" formula, i.e. at all stages of its implementation (including already ongoing), is an highly hostile action. This is clearly to be a "shock therapy" for the Kiev authorities, showing president Trump's level of determination to meet his goals.
Ukraine will be able to defend itself for at least six months
Will this sanction prove effective? Depends on how it affects the capabilities of Ukrainian armed forces. Contrary to the current opinion, the main problem in the coming months will not be the deficiency of artillery ammunition. Ukrainian barrel artillery (armatohaubice) uses 4 basic calibers of missiles: 2 post-missile (122 and 152 millimetres) and 2 NATO standard (105 and 155 millimetres). Ammunition to the russian cannonhaubic was not supplied from the US, primarily from the resources of the states of the erstwhile block of socialist states and intervention purchases from countries utilizing Russian weapons mainly from Asia and Africa.
In the case of Western production cannon ammunition, production has increased importantly and is now higher in Europe than in the USA. If EU countries decide to redirect all production to Ukraine on an ad hoc basis, this will safe the coming months. In addition, The Ukrainian army surely has strategical reserves which will let it to proceed fighting for at least the next six months.
The suspension of US satellite designation support will not be crucial, as Ukrainians have been utilizing commercially purchased satellite imaging links for more than 2 years. A bigger problem will be cutting off the AWACS-based early informing system. However, in a comparatively short period of time it is possible to replace these machines with aircraft equipped with European countries.
This will hurt Ukraine
A bigger problem will be the provision of missiles to HIMARS multi-guided rocket launchers and PATRIOT anti-aircraft kits. In the case of HIMARS, it is not possible to get missiles in Europe. For the Ukrainian army, this is now an crucial means of demolition at a distance of up to 300 km, but may partially compensate for their deficiency of mid-range drones, modified NEPTUN anti-ship missiles and Storm Shadow/SCALP missiles.
European countries have limited anti-aircraft rocket reserves for the PATRIOT systems (Germany, the Netherlands, Greece), but their transportation would require a breach of the wartime strategical reserves. However, even then, this will not guarantee the level of US supplies. The PATRIOT systems supply protection primarily to the largest Ukrainian cities, so their deficiency will destruct primarily urban infrastructure and failure to the civilian population.
Ukrainian soldiers may begin to feel a deficiency of anti-tank weapons (Javelin and TOW launchers). Here, however, it may be valuable to help, for example, Sweden, which produces excellent grenade launchers Carl Gustav. It is worth noting that Ukraine resumed production of any types of weapons (e.g. AHS BOGDANA) and ammunition, mainly mortar.
Stopping American aid will not have a decisive effect on the situation on the front in the next fewer months. Nevertheless, we must anticipate a reconciliation motion from Kiev, who cannot afford to make the US an open enemy.