It's been just over a year since Japan's Nippon Steel bought U.S. Steel, after agreeing to invest $11 billion into the Pittsburgh-based icon by the end of 2028.Thus far, almost all of that money remains a promise.By the numbers: Nippon had invested less than $200 million through the end of March, according to recent disclosures.It expects to have invested a total of $580 million through the end of August, as part of $3.2 billion in approved projects (the largest of which isn't slated to end until early 2029).Nippon reaffirmed its $11 billion investment pledge, but didn't provide allocation info on the remaining $7.8 billion.Catch up quick: The Biden administration had blocked Nippon's acquisition on national security grounds that felt more like political pandering.President Trump also opposed the deal, but flipped after Nippon increased its investment commitment and included a non-financial "golden share" that gives the White House certain governance and veto rights.The big picture: Nippon appears to have stabilized U.S. Steel and retained its union workers. It's also projecting over $600 million in 2026 profits, which would be the company's best mark since 2023.Trump's steel tariffs have benefited both U.S. Steel and its domestic rivals, although a bit offset by relatively static steel spend in construction (despite the data center boom).The national security chatter has disappeared and Nippon says the U.S. government hasn't yet leveraged its golden share to impact management decisions.Nippon Steel shares in Tokyo have been mostly flat since the merger, while the value of its U.S.-listed ADRs — which are more thinly traded — have plunged.Yes, but: Nippon is under financial pressure from the acquisition, sparking some skepticism over its ability to make good on its full investment pledge.The company's leverage is nearly triple what it was before the merger, which contributed to a downgrade by S&P that was recently reaffirmed with a negative outlook.One union official recently told the Pittsburgh Tribune: "We have the exact same people and the exact same situation telling the exact same story ... I won't believe a word these people say until I see steel rolling."The bottom line: U.S. Steel spent nearly two years waiting to learn its fate. Now it's waiting for Nippon to put all of its money where its mouth was.