By Echo Wang and Sabrina ValleNEW YORK, July 31 (Reuters) - Defense technology company Space-Eyes has agreed to go public through a merger with special purpose acquisition company McKinley Acquisition Corp, in a deal valuing the combined business at $638 million, according to four people ‌familiar with the matter. President Donald Trump's son Eric Trump has recently become the third-largest private investor in the original Space-Eyes, which has ‌operated primarily as a research-and-development company and generated about $1 million in annual revenue, the people said. Eric Trump will serve as a strategic adviser to the combined business following the transaction, the ​people said, adding he helped introduce potential board candidates to the new public company. Representatives for Eric Trump did not respond to a request for comment. The deal reflects growing investor interest in defense technology companies as governments worldwide increase spending on drone detection, autonomous systems and AI-driven battlefield intelligence.