NAPLES, Italy — International Launch Services (ILS) Chief Executive Frank McKenna is leaving the company after six years and is being replaced by long-time Chief Financial Officer Phil Slack, ILS announced Nov. 20.

Reston, Va.-based ILS did not explain the reason for the abrupt change, which is effective immediately and is the latest management shakeup in the company in recent months. ILS’s chief commercial and technical officers also have been replaced, for reasons unrelated to each other.

Khrunichev Space Center of Moscow, the Proton rocket’s prime contractor and ILS’s principal owner, has seen a management change this year as its chief executive was forced to step down in the wake of Russian government complaints about recent Proton reliability.

ILS has little input into Proton’s manufacturing but is responsible for selling the rocket on the global commercial market. The vehicle thus far has not had a good year compared with Europe’s Ariane 5 ECA heavy-lift rocket, which is Proton’s principal competitor.

Commercial rocket sales ride not only the overall tides of the market but also what kinds of satellites are ordered. Owners of smaller satellites, which can be launched as secondary payloads on Ariane 5, often conclude that Evry, France-based Arianespace is a better match for their satellites, which otherwise would need to ride as solo passengers on Proton.

Under McKenna’s leadership, ILS has been trying to adapt Proton to be able to handle dual launches of smaller telecommunications satellites as a way to capture part of the market that is now wedded to Arianespace.

Peter B. de Selding was the Paris Bureau Chief for SpaceNews.