I'm not closely following, but is the theory behind your investment in CLF that they will get a bargain on US Steel (X) because they are able to leverage political connections in the US to block Nippon?
Seems more likely to me that X (current price $40.25) will simply decline to be bought for the pittance CLF is offering. That might cause CLF to rise, as the merger discount goes away. This could be another rationale to buy CLF.
X is profitable and has a debt/equity of only 39%, so there shouldn't be any immediate pressure on them to fire sale the company. I suppose the worst case scenario for CLF shareholders is for the merger to go through and buyer's remorse to set in. The vast majority of mergers destroy shareholder value, though this one could create a monopoly in some markets.