Leaders and China and US must set clear rules on espionage
The United States has won respect around the world for its defence of human rights. But it is a record that can only be sustained by a credible claim to the high moral ground.
The US must expect to be held to the standards it continues to expect of others.
To the dismay of America's friends, that claim has been seriously eroded since the 9/11 attacks by rights abuses such as prolonged detention without trial and mistreatment of terrorist suspects.
Another example is to be found in the Edward Snowden revelations of the global scale of electronic spying on foreign friends and foes alike.
Respect for human rights and the rule of law begins at home.
The cases of two Chinese American scientists, both naturalised US citizens, have raised concerns that amid worries over Chinese espionage, investigators have become reckless or prejudiced in targeting innocent people.
On the face of it, Sherry Chen and Professor Xiaoxing Xi are representatives of America's proud immigrant heritage.
Last year federal agents arrested Chen, a government hydrologist, on espionage-related charges.
The Justice Department ultimately dropped the case, but the government says it plans to fire her from the job she has held with the US National Weather Service for eight years on similar grounds to the prosecution, citing "untrustworthiness".
It sounds more like face-saving at the expense of her rights.
Xi has also learned that the government has dropped charges of spying for sharing a schematic with a Chinese colleague. Their lawyer says prosecutors acted after hearing explanations of the facts.
More aggressive investigations and prosecutions are to be expected as a result of the US administration's alarm at hacking and cybersecurity threats. But the way these cases have unfolded suggests irrational apprehensions of security threats, not to mention a pattern of ethnic targeting.
In a speech to businessmen in Washington, President Barack Obama has done nothing to restore a sense of balance, ahead of talks with President Xi Jinping that will focus on cybersecurity. He said he accepted that China and other nations including the US would pursue traditional espionage, but stealing commercial secrets was "an act of aggression that has to stop".
In the wake of former CIA contractor Snowden's revelations of US spying on Chinese companies, the attempt to draw such a distinction reflects the sensitivity of the issue that the two leaders will address.