"The grand theses may resonate, but implementation would pit Trump against the whole bipartisan [foreign policy] establishment, including the [US Joint] Chiefs of Staff," Clarke told Sputnik on Friday.
Clarke acknowledged that Trump had been consistent in his calls for other NATO nations to increase their share of contributing to the costs of their own defense and other alliance activities.
"The themes Trump sounded are ones that are familiar from him, so they appear to have grounding in his thinking rather than being opportunistic," Clarke suggested.
Clarke also observed that Trump’s demand for increased defense spending by other NATO states was not unique to him and had even been expressed publicly by US President Barack Obama in recent months.
"The demand that NATO and other alliance members stop being 'free riders' is not unknown among mainstream figures,” Clarke explained. “So these ideas are less idiosyncratic than other of Trump's proposals.”
Trump’s policy critics were likely to argue that keeping major US forces in Europe was essential to America’s foreign policy agenda in the region, Clarke suggested.
"The US attachment to NATO is more grounded on a 'forward' interpretation of US interests which needs a major ground presence in Europe,” he stated. “Without this the US would have much less influence in Europe.”
Clarke maintained that for many years European leaders had quietly taken advantage of this rationale to reject repeated US requests that they increase their own financial and military contributions to NATO.
Trump would have to take on his own Republican Party as well as defense and foreign policy interests to push through the changes he had promised, Clarke foresaw.
"I can't see that changing under a President Trump unless he really does want to overturn the entire Washington establishment, which would include the defense community, with which his party is in love," Clarke concluded.
Trump promised in his convention speech to rebuild the US military but also end its use in nation-building and democracy-supporting activities around the world, especially in the Middle East.