A note on this: When Trump met with Putin recently and questioned Putin on interference, it seems this meeting was simply an occasion for Trump to give Putin the opportunity to deny election interference.
According to reports, Trump asked Putin in a number of ways whether he or the Russian state was involved in the interference. Contrast that with Obama’s reported direct accusation and threat of counter measures. He reportedly said that the US can do things too. He accused Putin face to face based on CIA reports, which to him were sufficient and reliable evidence.
Trump on the other hands seemed to be in the dark about evidence. According to reports he did not accuse Putin of anything and instead approached the situation as if there were no evidence. Puzzling.