Washington (CNN) Fiona Hill, the top official on Russian affairs at the National Security Council, will depart the Trump administration this summer, according to two people familiar with the matter.

Hill, a former Brookings scholar and skeptic of Russian President Vladimir Putin, oversaw rocky Washington-Moscow ties over the past two and a half years. She's expected to remain in her current post at least through Trump's expected meeting with Putin at next week's G20 summit in Osaka, Japan.

She'll be replaced by Tim Morrison, an arms control specialist who currently serves as the top non-proliferation official at the NSC.

Morrison joined the administration last August and is widely considered a hardliner on nuclear policy -- his area of expertise. His hawkish views seem to align with those of White House national security adviser John Bolton who has worked toward transforming the NSC into an entity that is hyper-focused on executing the President's agenda by bringing in more political appointees and reducing the number of career officials on his staff.

An NSC spokesman declined to comment on personnel matters.

Read More