US Secretary of State Antony Blinken will return to Brussels this week for discussions on Iran, Afghanistan and Russian activities directed at Ukraine, a US official said as quoted by Reuters.

Blinken will join US Defense Secretary Lloyd Austin in Brussels, Reuters reported.

The official, speaking on condition of anonymity on Saturday, did not release additional details on the trip, according to Reuters report.

Austin was scheduled to visit NATO headquarters in Belgium on a trip that started on Saturday and also includes Israel, Germany and Britain, the Pentagon said last week.

Reuters reports that the trip by two of President Joe Biden’s Cabinet members coincides with increasing tensions over Russian activities near Ukraine’s eastern border, where Washington says Russia has amassed more troops than at any time since 2014, when it annexed Crimea.

Russian President Vladimir Putin accused Ukraine on Friday of “dangerous provocative actions” in Ukraine’s eastern Donbass region.

Turkey, a NATO ally, said on Friday the United States would deploy two warships to the Black Sea from April 14-15, according to Reuters.