Ukraine’s leader will meet with Pres­i­dent Don­ald Trump in Wash­ing­ton on Fri­day at a piv­otal mo­ment for his coun­try, one that hinges on whether he can per­suade Trump to pro­vide some form of U.S. back­ing for Ukraine’s se­cu­ri­ty against any fu­ture Russ­ian ag­gres­sion.

Dur­ing his trip to Wash­ing­ton, Pres­i­dent Volodymyr Ze­len­skyy’s del­e­ga­tion is ex­pect­ed to sign a land­mark eco­nom­ic agree­ment with the U.S. aimed at fi­nanc­ing the re­con­struc­tion of war-dam­aged Ukraine, a deal that would close­ly tie the two coun­tries to­geth­er for years to come.

Though the deal, which is seen as a step to­ward end­ing the three-year war, ref­er­ences the im­por­tance of Ukraine’s se­cu­ri­ty, it leaves that to a sep­a­rate agree­ment to be dis­cussed be­tween the two lead­ers — talks that are like­ly to com­mence Fri­day.