Ukrainian side of course is tempted the armament in case of attack at positions of the DPR and LPR. And this can provoke Russia to supply Donetsk and Lugansk with armament.
There is an opinion that Kiev can sell Javelin to DPR and very soot it will be in Moscow.
And the USA had to forbid the use of the armament not to raise the war, because the armament is defensive.
More probably that Kiev will follow the prohibition, because they are interested in armament supplies from NATO and the USA. This supply with Javelin had symbolic character, to show that the USA supports Kiev.