The US government has reserved the right to re-open its national security review of Alcatel's merger with Lucent in the event that the companies fail to comply with some of the restrictions placed on the transaction.

Although the committee that vets foreign takeovers of US assets approved the merger between the French and US telecommunications equipment makers last month, the condition, re-vealed in a recent regulatory filing, underscores how significantly the environment for foreign deals has changed since the Dubai ports debacle this year.