The sibling comments are very relevant, but I wanted to provide a marginally different perspective. You have to take not only what is being said, but _who is saying it_ into perspective.
In this case, this is a government official speaking to the press (i.e. in an official capacity). If they were to say "this was sabotage," that is a definite declaration that the government believes - again, officially and on the record - that an outside party has deliberately done material damage to their country. Given the general situation, it is not a huge leap to come to the interpretation that "this was an attack against our country, and possibly an act of war."
No government official would want to be within miles (or kilometers) of that sort of statement unless they have pretty much already internally decided from the top-down to escalate the situation. Almost no single government agent has the authority to escalate the situation in that manner. So what we end up with is "appears to be." This overtly says 'all available evidence points to this being the case, however something else cannot be ruled out.' (As a sibling comment suggests, it can also act as a type of propaganda). So it is not an official government declaration that another nation has damaged them, but they have reasons (probably both apparent and not) to believe what they are saying publicly.