Reeling under the financial and diplomatic impacts of its war in Ukraine, Russia has stepped up cooperation with China to expand its foothold in the Arctic, with significant implications for U.S. national security, according to a new private intelligence report.

Russian President Vladimir Putin has long prioritized military and economic expansion in the Arctic as a key facet of his geopolitical strategy and ambitions, and after the 2014 annexation of Crimea, he began cooperating with China in the region. But after it sought to limit the involvement of the People’s Republic, Russia recently has invited much greater Chinese participation, says the report by Strider Intelligence, a firm that focuses on open-source intelligence about China.