US President Donald Trump’s 50-day pause ahead of possible secondary sanctions on Russia gifts the Kremlin a window to exploit the incremental gains of recent weeks in Ukraine’s east.

If Trump now permits a substantial amount of U.S. weapons to continue to flow to Ukraine, that would mark an important change. Since Trump took office, many in Ukraine and European capitals have thought that might well be the best-case scenario for Ukraine, given the U.S. president's clear hostility to continuing U.S. donations.