Ha ha ha ha ha ha, did you just compare damage to a 'bridge inside borders' to a bridge over the ocean?
I compared a bridge across a large body of water to a bridge across an only slightly larger body of water. Whether the bridge goes from one country to another is largely irrelevant unless the leaders of one country or the other are idiots. After all, they would both have to pay part of the cost of any future repairs to that bridge, which is a powerful disincentive to bombing it in a fit of stupidity. If anything, the nature of such a bridge might even serve to stabilize relations between the two countries.
The only bottleneck there is a port and ports are much easier and faster to build than additional bridges to increase throughput.
Ports can only increase bandwidth. What shippers care about is latency. The only way you can improve latency with boats is to build faster boats, and the faster the boat, the less it can carry (and the more fuel it takes), so there are very real practical limitations involved.
A burning bridge stops all cargo from being moved, while a burning ship only stops that ship. Shipping docks are a scalable solution, while a bridge is a fixed throughput solution that cannot be scaled without building a second bridge.
A burning dock stops all cargo from being moved. Your point? You think that after Russia and the U.S. build a multi-billion-dollar bridge, one of them is going to suddenly decide to blow it up on a whim? Periods of international tension might very well close the bridge, but I can't imagine them being shortsighted enough to blow it up.
Also, bridges can be repaired pretty quickly these days, for the most part. When a tanker fire destroyed an elevated road segment in San Francisco back in 2007 and caused it to fall on top of another elevated road segment (requiring significant repairs), they had the lower segment repaired in eight days, and the upper one rebuilt in just 25 days. And with the floating bridge I described, assuming you build some extra segments, damage could be repaired in hours simply by towing another identical segment into place and fastening it to the adjacent segments. You just have to provide enough of a financial incentive to grease the wheels of the bridge building company.