U.S. President Barack Obama and Ukrainian President Petro Poroshenko have discussed ways to better control the uneasy border between Russia and eastern Ukraine.
Obama and Poroshenko spoke by phone on October 15.
The White House says they discussed how all sides must live up to a cease-fire deal signed last month in Minsk, as well as energy security, political reform, and Ukraine's effort to bolster its economy.
Obama praised the Ukrainian parliament's passage of legislation to fight corruption.
The call comes as Russian President Vladimir Putin is due to hold talks with Western leaders about Ukraine.
Putin will take part in a two-day Europe-Asia summit starting on October 16 in Milan.