It is very likely that the Russians are behind the leaked emails from the DNC but enforcing punishment may be difficult. The United States relationship with Russia is delicate and they are not going to admit their involvement in the email hacking. It is another show of Russian tactics to interfere with the U.S. political system.
Russia should be punished if they are found to be the ones behind the leaked e-mails from the DNC. The hacked e-mails are a gross invasion of privacy and illegal. If guilty, it is also a bold attempt to tilt the United States election in a manner they find favorable.
I do not think that Russia had anything to do with the leaked emails from the Democratic National Convention. However, if Russia is found to be involved in the leaking of th DNC emails, I think that they should be punished. Any breach of privacy, especially when breached through cyber crime, should be punishable, even if done internationally.
Although they were criminal acts, the DNC hacks exposed an attempt by the Democratic party to undercut Bernie Sanders' chances for the Democratic nomination. This kind of whistle blowing is essential for a true democracy, as it brings these kinds of shady backroom deals out into the light for all to see. In this case Americans should thank the Russians and not punish them.