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, which analysts say increasingly put key Ukrainian strongholds in the east in peril.

Russia is thought to be days or weeks away from surging into a heightened summer offensive, perhaps using the 160,000 troops Ukrainian officials have said are amassing near their front lines. But in the past two weeks, Russia has also made small but vital advances, placing its forces in a better position to cut off Ukrainian troops in three key towns – Pokrovsk, Kostyantynivka and Kupiansk – on the eastern front line.

The Kremlin appeared unperturbed by the new Trump deadline, Foreign Minister Sergey Lavrov saying on Tuesday: “Fifty days – it used to be 24 hours; it used to be 100 days; we’ve been through all of this.”

Analysts said the new time frame boded well for Russian President Vladimir Putin’s goals. Keir Giles from Chatham House wrote Tuesday that it also provided space for Moscow on the diplomatic stage. “The deadline of 50 days gives Russia plenty of time to concoct its own alternative plan, and once again outmanoeuvre Washington through a diplomatic ploy which Trump may well accept willingly… Trump’s latest extension of his notional deadlines for Putin extends Ukraine’s suffering for the same arbitrary period.”

John Lough, head of foreign policy at the New Eurasian Strategies Centre think tank, said the summer offensive had likely been underway for several months already, and that “the Russians are undoubtedly intensifying their efforts, both on the ground and in the air.” He said the recent aerial onslaught against Ukraine’s cities was perhaps a reflection of Moscow’s slow progress on the front lines, and aimed “to demoralize the population and zap its will to fight.”