By 0810 GMT, the pan-European STOXX 600 was 0.3% higher. Trading volumes are expected to normalize as investors return following New Year holidays.
The defense index rose 2.7% and hit its highest in two months. Technology and basic resources were also up 2.1% and 2%, respectively.
Investors will continue to eye the fallout from the dramatic capture of Venezuelan President Nicolas Maduro by U.S. forces over the weekend. President Donald Trump said on Saturday he was putting Venezuela under temporary American control.
Investors are also focusing on central banks, watching incoming data for clues on how quickly rate cuts could arrive.
Meanwhile, miners Glencore, Rio Tinto and Anglo American got a boost on the back of higher copper prices.
Shares of ASML, the world’s biggest supplier of computer chip-making equipment, rose 3.9%. Analysts at brokerage Bernstein upgraded the stock to “outperform” from “market perform” and raised their price target on the stock to 1,300 euros from 800 euros.