On 27 April 1812, Napoleon granted, the Russian Ambassador, Alexander Kurakin, an audience. Kurakin had instructions from Tsar Alexander that there would be no negotiations with Russia unless all French troops withdrew from Prussia to behind the Rhine. "What have your St. Petersburg people done with their heads, to think they can intimidate me with threats?" Napoleon supposedly responded . Kurakin pointed out that Napoleon's alliance with Prussia was directed against Russia. Napoleon let it be known that he now also had an alliance with Austria. Further, Napoleon said that he regretted that the Tsar should be ordering him to move his troops when Russian troops were now on the frontier of the Grand Duchy of Warsaw. The audience ended with Napoleon giving Kurakin a letter to deliver to Alexander. Napoleon ended this letter with a personal statement to Alexander: "Your majesty will however allow me to assure him that, were fate to conspire to make war between us inevitable, this would in no way alter the sentiments which Your Majesty has inspired in me, and which are beyond any vicissitude or possibility of change".
1.The Napoleon Series: Franco-Russian Diplomacy, 1810-1812 found here.
2. Adam Zamoyski, Moscow 1812: Napoleon`s Fatal March (New York: Harper Perennial, 2004), at 107