TOKYO, March 16 (Reuters) - Japan's Nikkei share average slipped on Friday morning in choppy trade as uncertainty over U.S. political issues sapped investors' risk appetite, with index-heavy stocks such as Fanuc and TDK underperforming.
The Nikkei fell 0.3 percent to 21,737.95 in midmorning trade after opening up slightly higher. For the week, the benchmark index has gained 1.3 percent.
The dollar was 0.3 percent lower at 106.020 yen following a report by the Washington Post that U.S. President Donald Trump has decided to remove H.R. McMaster as his national security advisor.
Also souring sentiment was news that U.S. Special Counsel Robert Mueller has subpoenaed the Trump Organization for documents, including some related to Russia, the New York Times reported on Thursday, citing two people briefed on the matter.
Analysts said that uncertainty over U.S. political matters is casting a shadow on investment in risky assets, however, downside should be limited thanks to the Bank Of Japan's buying of exchange-traded funds to support the market.
The central bank bought 73.5 billion yen of ETFs on Wednesday and Thursday, respectively.
Fanuc Corp shed 1.4 percent, TDK Corp stumbled 2.3 percent and Tokyo Electron declined 1.1 percent.
Utility shares were also sold. Kansai Electric Power Co dropped 2.0 percent and Chubu Electric Power Co fell 1.4 percent.
The broader Topix dropped 0.1 percent to 1,741.41. (Editing by Simon Cameron-Moore)