An Israeli internet firm has abandoned its bid to acquire a smaller American rival after the US government raised security concerns.
The US had concerns over classified computer information
Israel's Check Point Software Technologies ditched plans to buy Sourcefire after a US national security investigation.
US officials told Check Point that the transaction could threaten some of the government's most sensitive IT systems.
The deal was called off when the two parties failed to reach an agreement.
The Committee on Foreign Investment in the United States (CFIUS), which is responsible for examining acquisitions of US companies by foreign companies, has conducted only 25 full investigations out of a total of 1,600 business transactions that came before it.
The committee recently looked into a controversial takeover plan by an Arab company, Dubai Ports World, involving six key US ports.
The Dubai Ports deal was given the go-ahead by the committee but has since been abandoned.
If the Check Point sale, made public early last October, had taken place, it would have acquired all Sourcefire's patents, source codes and blueprints for its software, as well as employees' expertise.
The FBI and the Pentagon had particular concerns regarding a particular type of so-called Snort software, which protects certain classified US military and intelligence computers.
"Given the CFIUS concerns, [Sourcefire] might have to limit [its] potential partners," said Peter Kuper of Morgan Stanley.
"A US acquirer would be a lot simpler and cleaner," Mr Kuper added.
Check Point told investors about the higher-level US investigation on February 13.
In about half of the investigations conducted by CFIUS, companies withdrew from proposed deals rather than face rejection.