The danger of outright war, if not nuclear war, is more on the action from the leadership in Washington than from Pyongyang, at least for now.
The North Korean leadership KNOW they will die if they go too far, while that is not a worry for the leaders on the other side. Their personal safety are not threatened.
The NK’s nuclear capability is limited, if they are at all able to fit a nuclear warhead on their rockets yet, while the other side has enough nuclear weapons to kill us all and have proven their capability.
Both sides have enough conventional fire power to flatten both Koreas and part of Japan. Guam is also within reach.
How much the lives of millions of Koreans (North and South) and a few thousand others, count in the deliberations is left to be seen, but let us hope that “the adults” in the WH can keep this in check.
The OP asked about what affect a war with North Korea will have on the shipping industry. (By that I assume he means the American shipping industry??)
The answer is probably none. By the time the ships in the reserve fleet gets ready to sail the war will be over, with no winner, only losers.
If anybody is stupid enough to use nuclear weapons, it will be over for all of us, as China and possibly Russia will get involved, with enough nukes to kill us all one more time.