US Air Force General Alexus Grynkewich was speaking after decisions by President Donald Trump's administration to withdraw some 5,000 troops from Germany and cancel deployment of long-range Tomahawk missiles.Speaking to reporters after a meeting of NATO military chiefs in Brussels, Grynkewich said the decision was the only such move he was aware of "in the near-term" and would not affect the alliance's ability to execute its defense plans.His comments came as Polish officials seek clarity after the Pentagon halted the planned deployment of about 4,000 American troops to Poland, triggering consternation.Polish Defense Minister Władysław Kosiniak-Kamysz insisted on Tuesday after speaking to US war secretary Pete Hegseth that "no decision has been made to reduce US military capabilities in Poland.” European governments say they have heeded US President Donald Trump's call to spend more on defense and take more responsibility for the continent's security. But they fear a hasty withdrawal of US troops and weapons could leave Europe vulnerable to a military attack from Russia, although Moscow denies any such intention.Drawdown to take yearsGrynkewich said there would be further withdrawals of US troops in Europe, which number roughly 80,000, but that would happen as European forces grow to fill the gap."As the European pillar of the alliance gets stronger, this allows the US to reduce its presence in Europe and limit itself to providing only those critical capabilities that allies cannot yet provide," said Grynkewich, NATO's Supreme Allied Commander."I can't really give you an exact timeline; it's going to be an ongoing process for several years," he added.While Europe would take more responsibility for conventional defense, this would happen "with continued critical backing from American capabilities, which are being adjusted," Grynkewich said.NATO relies on the U.S. for a range of critical capabilities such as command and control systems, satellite-based intelligence and communications, strategic bombers and the US nuclear umbrella, officials and analysts say.(This story uses reporting from Reuters)