April 23 (Reuters) - The following are the top stories in the Wall Street Journal. Reuters has not verified these stories and does not vouch for their accuracy.
* China's top nuclear experts have increased their estimates of North Korea's nuclear weapons production well beyond most previous U.S. figures, suggesting Pyongyang can make enough warheads to threaten regional security for the U.S. and its allies. (on.wsj.com/1DeVtJM)
* Petrobras finally put a price tag on the impact of a corruption scandal, writing off $2.1 billion due to alleged graft, in addition to a $14.8 billion asset-impairment charge.(on.wsj.com/1OI5tSH)
* FCC staff threw up a significant roadblock to Comcast Corp's proposed acquisition of Time Warner Cable Inc , recommending a procedural move that could potentially sink one of the media industry's biggest mergers in years. (on.wsj.com/1JwuEGb)
* The Pentagon plans to open its first office in Silicon Valley in an effort to tap commercial technology to develop more advanced weapons and intelligence systems. (on.wsj.com/1FfQQW7)
* E-commerce site Jet.com has yet to launch its marketplace, but it has landed a $600 million valuation and has been lauded for its business model. (on.wsj.com/1Eu7KBp)
Compiled by Rama Venkat Raman in Bengaluru